University of Southern California Dissertations and Theses

Properties and applications of dipyrrin-based molecules in organic photovoltaics

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Properties and applications of dipyrrin-based molecules in organic photovoltaics

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Content !
!
Properties!and!Applications!of!
Dipyrrin3Based!Molecules!in!
Organic!Photovoltaics!
!
by#
#
John!Jun3An!Chen!
#
#
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A#dissertation#submitted#in#partial#fulfillment#of#the#requirements#for#
the#degree#of#
Doctor#of#Philosophy#
(Chemistry)#
Faculty#of#the#USC#Graduate#School#
University#of#Southern#California#
#
May#12,#2017#
#
#
#
#
#
#
Doctoral!Committee:!
Professor#Mark#E.#Thompson,#Chair#
Assistant#Professor#Brent#C.#Melot#
Professor#Sandeep#Gupta#
! i!
Dedications+
!
!
!
!
To!my!grandparents,!
whom!I!miss!dearly,!
!
To!my!kind!parents,!
!who!supported!the!pursuit!of!this!degree!in!every!way!imaginable,!
!
To!my!loving!wife,!Dan,!
for!her!extraordinary!patience!and!encouragement,!
!
To!my!son,!Oliver,!
whose!smiles!made!writing!much!more!enjoyable,!
!
And!to!the!wild!Inori,!
whom!I!promised!infinitely!more!play@time!in!the!future.! !
! ii!
Acknowledgements+
!
I!would!like!to!thank!my!advisor,!Professor!Mark!Thompson,!for!all!the!
support!and!opportunities!he!has!given!me!during!my!graduate!career.!!None!of!the!
work!in!this!dissertation!would’ve!have!been!possible!without!him.!!Under!his!
guidance,!I!am!grateful!to!have!become!an!independent!researcher,!a!problem!
solver,!and!an!experienced!educator.!!Most!importantly,!I!would!like!to!highlight!the!
research!freedom!Prof.!Mark!Thompson!has!given!me,!allowing!me!to!pursue!both!
the!synthesis!of!brilliantly!colored!molecules!as!well!as!understanding!the!complex!
process!in!the!fabrication!of!organic!solar!cells.!
I!would!like!to!thank!my!committee!members,!Prof.!Brent!Melot,!Prof.!
Sandeep!Gupta,!Prof.!Richard!Brutchey,!and!Prof.!Susumu!Takahashi,!for!taking!the!
time!out!of!their!busy!schedule!to!participate!in!my!screening,!qualifying!exam!and!
defense.!
I!am!grateful!to!have!become!part!of!the!USC!Chemistry!community.!!I!
appreciate!all!the!help!and!assistances!I!have!received!throughout!my!graduate!
career!from!the!faculties!of!the!USC!Chemistry!Department!such!as!classes!with!Prof.!
Richard!Brutchey,!NMR!discussions!with!Prof.!Travis!Williams,!and!solving!crystal!
structure!with!Prof.!Ralf!Haiges!to!name!a!few.!
Prof.!Peter!Djurovich!has!been!part!of!countless!invaluable!scientific!
discussion!during!my!graduate!career.!!His!extensive!knowledge!and!guidance!has!
aided!me!numerous!times!when!I!am!unsure!what!the!next!step!should!be.!
! iii!
I!owe!Judy!Fong!an!awful!lot!of!gratitude!for!all!the!help!she!has!given!the!
group!and!me.!!She!has!facilitated!everything!imaginable!for!me,!from!tracking!
missing!chemicals!to!enforcing!laboratory!safety.!!I!could!always!count!on!her!to!
have!an!answer!for!me!whenever!I!have!a!question.!!Without!her!invaluable!
assistance!throughout!the!years,!it!probably!would’ve!taken!me!much!longer!to!
complete!this!degree.!
I!would!like!to!also!thank!Michele!Dea!and!Magnolia!Benitez!for!their!help.!!I!
appreciate!all!the!behind@the@scene!efforts!they!put!in!to!help!with!setting!up!
departmental!events,!courses,!answering!my!questions,!and!making!the!process!of!
graduating!much!easier.!!I!would!like!to!also!acknowledge!Rafael!Valdivia!for!his!
service!as!our!hazardous!waste!technician!and!all!the!times!he!came!by!the!lab!to!
pick!up!our!waste!even!on!short!notices.!!His!patience!and!advices!have!been!
instrumental!in!the!safety!and!chemical!upkeep!of!the!lab.!!Over!the!last!year,!I!have!
come!to!rely!on!Bruno!Herreros!for!all!problems!concerning!our!inventory!system.!!!
I!would!like!to!thank!him!for!always!responding!quickly!and!fixing!the!inventory!
system.!
! I!am!eternally!grateful!to!be!part!of!the!MET!Lab!and!the!wonderful!
colleagues!and!friends!I!have!met!in!this!lab.!!I!have!come!to!appreciate!each!
individual’s!part!in!the!lab!and!would!like!to!acknowledge!everyone,!past!and!
present,!for!his!or!her!help!in!keeping!this!lab!functional.!!Without!their!companies,!
working!in!the!lab!would!have!been!much!less!enjoyable.!!I!am!glad!there!are!always!
people!willing!to!help!and!discuss!science!with.!!A!complete!list!of!the!lab!would!be!
too!long,!but!I!genuinely!appreciate!everyone!in!the!lab!for!being!part!of!my!
! iv!
graduate!experience.!!I!would!like!to!specially!thank!my!good!friends,!Dr.!Patrick!
Erwin!and!Dr.!Sarah!Conron,!for!the!collaborations!on!BODIPY!projects,!and!Dr.!
Denise!Femia!for!organizing!the!annual!pumpkin@carving!contest.!
I!would!like!to!thank!my!family!for!the!wholehearted!and!unconditional!
support!they!have!given!me!during!my!graduate!career.!!Without!them,!it!would’ve!
been!a!much!more!arduous!and!difficult!endeavor.!!I!would!like!to!thank!my!wife!
especially!for!her!encouragement!and!keeping!me!on!my!toes!to!finish!this!
dissertation.!!I!also!appreciate!her!attendance!to!all!the!departmental!events!even!
when!she!doesn’t!want!to.!
Lastly,!I!would!like!to!thank!the!National!Science!Foundation!and!Nanoflex!
Power!Corporation!for!their!generous!financial!support.!
!
!
+ +
! v!
Table+of+Contents+
+
Dedications!..................................................................................................................................................!i+
Acknowledgments!..................................................................................................................................!ii+
Table+of+Contents!.....................................................................................................................................!v+
List+of+Figures!........................................................................................................................................!viii+
List+of+Schemes!..........................................................................................................................................!x+
List+of+Tables!.............................................................................................................................................!xi!
Abstract!.........................................................................................................................................................!1+
Chapter+1.!Introduction!.........................................................................................................................!2!
1.1!Energy!Demand!and!Outlook!.................................................................................................!3!
1.2!Fundamentals!of!Organic!Photovoltaics!...........................................................................!3!
1.3!Challenges!in!Organic!Photovoltaics!..................................................................................!8!
1.4!Presented!Research!................................................................................................................!11!
1.5+References!...................................................................................................................................!13!
Chapter+2.!Impact!of!π-extension!on!BODIPY!Dyes!..............................................................!14!
2.1+Introduction!...............................................................................................................................!14+
2.2+Synthesis!of!bDIP!and!bDIP@c!.............................................................................................!14+
2.3+Synthesis!of!iDIP!.......................................................................................................................!17+
2.4+Material!Properties!of!bDIP!and!iDIP!..............................................................................!19+
2.5+Impact!of!Fusion!Mode!on!Photophysical!Property!.................................................!22+
2.6+Conclusion!...................................................................................................................................!26+
2.7+Experimental!.............................................................................................................................!28+
2.8!NMR!Spectra!..............................................................................................................................!29+
2.9 TD-DFT Calculations ............................................................................................32
2.10 Crystallography Details .......................................................................................32
2.11 References ............................................................................................................34
Chapter+3.+OPV!Application!of!Red!BODIPY!Dye,!bDIP!.........................................................!36+
3.1+Introduction!...............................................................................................................................!36+
3.2+Thin!Film!Properties!of!bDIP!..............................................................................................!37+
! vi!
3.3+Bilayer!Photovoltaic!Devices!..............................................................................................!37! +
3.4+Neutron!Reflectivity!...............................................................................................................!40+
3.5+Planar@Mixed!Heterojunction!Photovoltaic!Devices!.................................................!42+
3.6+Conclusion!...................................................................................................................................!46+
3.7+Experimental!.............................................................................................................................!47+
3.8+References!...................................................................................................................................!50+
Chapter+4.+Nitrile@Functionalized!BODIPY!for!C60!Sensitization!.......................................!53+
4.1+Introduction!...............................................................................................................................!53+
4.2+Synthesis!of!cDIP!......................................................................................................................!54+
4.3+Material!Properties!of!cDIP!.................................................................................................!56+
4.4+cDIP!as!Electron!Acceptor!....................................................................................................!57+
4.5+cDIP!as!C60!Sensitizer!.............................................................................................................!58+
4.6+Conclusion!...................................................................................................................................!64+
4.7+Experimental!.............................................................................................................................!65+
4.8+NMR!Spectra!..............................................................................................................................!67+
4.9+References!...................................................................................................................................!69!
Chapter+5.!!Synthesis!of!Near@Infrared!BODIPY!Dyes!............................................................!72!
5.1!Introduction!...............................................................................................................................!72!
5.2!Method!A:!Retro@Diels!Alder!...............................................................................................!72!
5.3!Method!B:!Dihydro!Intermediate!Approach!................................................................!75!
5.4!Properties!of!nDIP!Derivatives!..........................................................................................!77!
5.5!Conclusion!...................................................................................................................................!79!
5.6!Experimental!.............................................................................................................................!80!
5.7!NMR!Spectra!..............................................................................................................................!81!
5.8!References!...................................................................................................................................!84!
Chapter+6.+Progress!Towards!Meso@Linked!BODIPY!Dimers!..............................................!86!
6.1+Introduction!...............................................................................................................................!86!
6.2+One@Pot!Synthesis!of!meso&Linked!BODIPY!Dimer!...................................................!89+
6.3+Radical!Dimerization!of!BODIPY!Dyes!............................................................................!91!
6.4+Palladium!Cross@Coupling!BODIPY!Precursors!..........................................................!96!
6.5+Biphenyl@Bridged!BODIPY!Dimers!...................................................................................!99!
! vii!
6.6+Conclusion!.................................................................................................................................!100!
6.7+Experimental!...........................................................................................................................!101!
6.8!NMR!Spectra!............................................................................................................................!102!
6.9+References!.................................................................................................................................!108!
Bibliography!..........................................................................................................................................!112!
+ +
! viii!
List+of+Figures+
+
Figure+1.1!Device!Architecture!and!Active!Layer!Structure!of!OPVs!.................................!5!
Figure+1.2!Charge!Generation!Process!in!OPV!.............................................................................!7!
Figure+1.3!Current@Density!Versus!Voltage!Plot!for!a!Typical!OPV!Device!.....................!8!
Figure+1.4!Visible!and!NIR!regions!of!Solar!Flux!and!Energetic!Gap!Between!
Materials!................................................................................................................................!9!
Figure+2.1!Absorption!Spectra!and!Chemical!Structures!of!RDA@bDIP,!bDIP,!and!!
iDIP!........................................................................................................................................!20!
Figure+2.2!Crystal!and!Packing!Structures!of!bDIP!and!iDIP!..............................................!20!
Figure+2.3!Calculated!Energies!and!Cyclic!Voltammograms!of!bDIP!and!iDIP!...........!21!
Figure+2.4!Molecular!Interaction!Between!BODIPY!Core!and!Butadiene!!
Fragment!.............................................................................................................................!23!
Figure+2.5!Molecular!Orbitals!of!BODIPY,!bDIP,!and!iDIP!....................................................!25!
Figure+2.6!Potential!Energy!Diagrams!for!bDIP!and!iDIP!....................................................!27!
Figure+3.1!Structure!of!Parent!BODIPY!and!bDIP!and!Solution!&!Thin!Film!
Absorptions!and!Emissions!of!bDIP!........................................................................!36!
Figure+3.2!J&V!Plot!and!bDIP/C60!Bilayer!Device!Structure!..................................................!38!
Figure+3.3!Summary!of!PV!Performance!on!Thickness!Dependence!of!bDIP!..............!39!
Figure+3.4!Neutron!Reflectivity!Fitting!and!Modeling!of!Device!Structure!..................!40!
Figure+3.5!J&V!and!EQE!Plots!of!Rate!Dependence!in!bDIP:C60!PMHJ!Devices!.............!43!
Figure+3.6!AFM!Images!of!1:1!bDIP:C60!Films!...........................................................................!44!
Figure+3.7!J&V!and!EQE!Plots!of!Composition!Dependence!in!bDIP:C60PMHJ!!
Devices!.................................................................................................................................!45!
Figure+4.1+Structure!and!Absorption!Profiles!of!CuPc!and!C60!..........................................!54!
Figure+4.2+Absorption!&!Emission!Plots!and!Cyclic!Voltammogram!of!cDIP!!.............!56!
Figure+4.3+Molecular!Structure!and!HOMO!&!LUMO!Energies!for!CuPc,!C60,!!
and!cDIP!..............................................................................................................................!57!
Figure+4.4+Thin!Film!Absorptions!of!cDIP!blends!and!PL!Quenching!of!cDIP!.............!58!
Figure+4.5+J&V!Plot!of!CuPc/cDIP!Devices!and!AFM!Image!of!cDIP!Film!........................!58!
! ix!
Figure+4.6+J&V!and!EQE!Plots!of!cDIP@Sensitized!Devices!.....................................................!59!
Figure+4.7+AFM!Images!of!cDIP:C60!Films!....................................................................................!61!
Figure+4.8!J&V!and!EQE!Plots!of!cDIP/C60!Devices!...................................................................!62!
Figure+4.9!J&V!and!EQE!Plots!of!cDIP@Sensitized!Devices!with!C60!Interfacial!!
Layer!.....................................................................................................................................!63!
Figure+5.1+Synthesis!of!RDA@Type!nDIP!derivatives!..............................................................!73!
Figure+5.2+UV@Vis!Absorption!of!RDA@nDIP!Before!and!After!Heating!..........................!74!
Figure+5.3+Synthesis!of!Dihydro@Type!nDIP!derivatives!......................................................!76!
Figure+5.4+Absorption!&!Emission!Plots!and!Cyclic!Voltammograms!of!nDIP!
derivatives!..........................................................................................................................!78!
Figure+6.1!First!Reported!Synthesis!of!Meso&Linked!BODIPY!Dimers!............................!90!
Figure+6.2+One@Pot!Synthesis!of!Meso&Linked!BODIPY!Dimers!.........................................!91+
Figure+6.3+Oxidative!Reaction!and!Electron!Distributions!of!Cyanine!Dyes!................!92!
Figure+6.4+Oxidative!Reaction!and!Electron!Distributions!of!BODIPY!Dyes!................!93!
Figure+6.5+Absorption!&!Emission!Plots!and!Cyclic!Voltammograms!of!!
cl@BDPs!.................................................................................................................................!94!
Figure+6.6!Reductive!Conditions!for!cl@BDPs!............................................................................!95!
Figure+6.7+Stability!of!BODIPY!Compounds!in!Basic!Conditions!......................................!98!
Figure+6.8+Molecular!Structure!and!yields!of!Biphenyl@Bridged!BODIPY!Dimer!.......!99!
! !
! x!
List+of+Schemes+
+
Scheme+1.1!A!Summary!of!BODIPY!Strategies!and!Modifications!Presented!.............!11!
Scheme+2.1!Synthesis!of!bDIP!and!bDIP@c!..................................................................................!15!
Scheme+2.2!Synthesis!of!iDIP!............................................................................................................!18!
Scheme+4.1!Synthesis!of!cDIP!...........................................................................................................!55!
Scheme+5.1!Structure!of!bDIP!and!nDIP!......................................................................................!72!
Scheme+6.1!SBCT!Molecules!and!Synthetic!Strategies!for!BODIPY!Dimers!.................!88!
Scheme+6.2!Synthesis!of!cl@BDP!......................................................................................................!94!
Scheme+6.3!Synthetic!Conditions!for!Pd!Cross@Coupling!BODIPY!Precursors............!97!
! !
! xi!
List+of+Tables+
+
Table+2.1!Optimization!Conditions!for!iDIP!Synthesis!..........................................................!18!
Table+2.2!Physical!Properties!of!bDIP!and!iDIP!.......................................................................!20!
Table+2.3!Computational!Outputs!for!bDIP!and!iDIP!.............................................................!25!
Table+3.1!Neutron!Reflectivity!Outputs!.......................................................................................!41!
Table+3.2!PV!Summary!of!Rate!Dependence!in!bDIP:C60!PMHJ!Devices!........................!43!
Table+3.3!PV!Summary!of!Composition!Dependence!in!bDIP:C60!PMHJ!Devices!.......!45!
Table+4.1!PV!Summary!of!cDIP@Sensitized!Devices!................................................................!60!
Table+4.2!PV!Summary!of!cDIP/C60!Devices!..............................................................................!62!
Table+4.3!PV!Summary!of!cDIP@Sensitized!Devices!with!C60!Interfacial!Layer!...........!63!
Table+5.1!Physical!Properties!of!nDIP@c!and!RDA@nDIP@c!....................................................!78!
Table+6.1+Physical!Properties!of!cl@BDP!and!cl@me4@BDP!.....................................................!94!
Table+6.2!Reduction!Potential!of!Reducing!Agents!.................................................................!95!
!
!
! 1!
Abstract(
!
Solar!energy!contains!a!substantial!amount!of!available!energy!to!supply!mankind’s!
demand!for!power!and!innovation.!!Of!the!emerging!technologies,!organic!photovoltaics!
(OPVs)!are!promising!costB effective!and!lightB weight!alternatives!over!traditional!silicon!
solar!cells.!!The!organic!absorbers!used!in!OPVs!are!small!molecular!dyes!that!are!favored!
for!their!high!absorptivity,!wellB defined!molecular!structure,!and!synthetic!versatility.!
Boron!dipyrrins,!or!BODIPY,!dyes!are!a!class!of!highly!absorbing!materials!
commonly!used!for!biological!imaging!and!fluorescence!tagging,!but!underutilized!in!the!
field!of!OPVs.!!Recent!works!have!shown!them!as!promising!candidates!for!improving!
power!conversion!efficiency!and!understanding!fundamentals!of!OPVs.!!By!tuning!the!
chemical!structure,!it!is!possible!to!modify!the!optical!and!electronic!properties!of!the!
BODIPY!to!perform!different!roles!in!an!OPV!device.!
A!series!of!BODIPY!were!synthesized!to!improve!their!absorption!profile!in!the!red!
and!nearB infrared!region!(Chapter!2!&!5).!!!This!allows!the!donor!material!to!complement!
the!commonly!used!electron!acceptor,!C60,!covering!a!larger!portion!of!the!solar!spectrum!
(Chapter!3).!!ElectronB withdrawing!groups!were!added!to!a!BODIPY!core!to!enable!its!
function!as!an!electron!acceptor.!!The!resulting!dye!was!used!as!a!C60!sensitization,!and!
indicated!efficient!energy!transfer!and!broadened!spectral!coverage!(Chapter!4).!!Finally,!
synthetic!studies!were!examined!to!investigate!the!synthetic!accessibility!of!BODIPY!
dimers!(Chapter!6).!!These!molecules!exhibit!interesting!symmetry!breaking!behavior!that!
can!be!applied!to!improving!OPV!performance.!
! 2!
Chapter(1.(
Introduction(
1.1(Energy(Demand(and(Outlook(
Addressing!the!ever/growing!needs!of!the!human!population!will!be!a!perpetual!
challenge!for!the!modern!human!race.!!Access!to!clean!air!and!water,!affordable!food,!and!
sustainable!shelter!mark!the!basic!necessity!for!human!survival.!!However,!as!the!society!
and!population!as!a!whole!begin!to!industrialize!and!advance!technologically,!additional!
resources!are!needed!to!drive!further!growth.!!Refrigeration,!transportation,!lighting,!
Internet,!automated!manufacturing,!and!computer!power!are!all!possible!because!of!the!
increasing!availability!of!electricity!available!from!the!industrial!age!to!the!modern!age.!!!
Since!its!discovery,!fossil!fuels!have!become!an!intrinsic!part!mankind’s!innovation!and!
civilization!growth,!fueling!all!efforts!with!its!cheap!and!accessible!source!of!energy.!!As!the!
consumption!of!gasoline,!coal,!and!natural!gas!rise!exponentially,!the!quality!of!living!for!
the!developing!and!developed!world!increased!substantially.!!It!is!estimated!that!total!
energy!consumption!will!increase!from!the!current!18!TW!to!over!25!TW!by!the!year!2035!
and!to!30!TW!by!2050.
1
!!While!the!positive!impacts!of!energy!consumption!were!marveled!
with!technological!growth,!the!negative!effects!of!burning!fossil!fuel!were!not!recognized!
until!recently.!
Numerous!and!often!permanent!environmental!effects!were!resulted!from!
mankind’s!harvest!of!fossil!fuel.!!Mountains!and!forests!were!cleared!for!coal,!while!oil!
tankers!and!pipelines!accident!led!to!massive!contamination!in!both!urban!and!natural!
habitats.!!Despite!these!immediate!consequences,!the!drive!for!improvement!and!change!
! 3!
has!still!been!slow!to!materialize.!!It!was!not!until!the!recent!decades!that!scientists!began!
to!document!and!quantify!the!invisible!and!hidden!impacts!of!fossil!fuel!consumption.!!
From!the!enormous!dumping!of!greenhouse!gases!into!our!atmosphere!to!the!acidification!
of!the!ocean,!long/term!consequences!have!begun!to!emerge.!!Every!year,!record!droughts!
and!heats!as!well!as!intensifying!storms!are!manifesting!in!areas!that!have!never!
experienced!these!disasters!before.!!These!phenomenon!produces!hidden!cost!unaccounted!
for!in!the!cost!of!fuel!sources!that!ultimately!result!in!economic!and!environmental!burden!
on!society.!!With!these!human/induced!climate!change!progress!to!the!verge!of!
irreversibility,!it!is!vital!that!a!new!source!of!clean!energy!be!implemented!to!start!
alleviating!the!effects!of!global!warming!and!climate!change.!
Renewable!energy!has!been!developing!in!the!recent!decades.!!Potential!sources!of!
clean!energy!include!wind,!hydro,!geothermal,!and!solar.!!No!one!particular!type!can!solve!
the!energy!problem,!but!rather!much!like!investment,!having!a!portfolio!of!energy!sources!
is!the!key!to!be!energetically!clean!and!self/sufficient.!!Countries!near!the!coast!may!rely!
heavily!on!wind!turbines!and!hydropower!while!landlocked!countries!may!rely!more!of!
geothermal!or!solar!energy.!!Of!all!the!available!clean!energy,!hydropower!is!probably!the!
most!prevalent!taking!up!to!74%!of!global!consumption!based!on!the!U.S.!Energy!
Information!Agency.
1
!!However,!solar!energy!has!the!most!available!energy!by!far!
compared!to!the!other!sources.!!For!example,!it!is!estimated!that!hydropower!can!
theoretically!produce!up!to!1!TW!given!all!the!feasible!locations!are!utilized,!while!the!sun!
produces!about!96,000!TW!of!energy.
1
!!While!it!is!obviously!impossible!to!collective!the!
entirety!of!that!energy,!it!is!encouraging!that!we!only!need!to!capture!a!small!fraction!of!the!
available!energy!to!fuel!the!demand!of!mankind.!!With!a!conservative!average!power!
! 4!
conversion!efficiency!(PCE)!of!12%,!we!are!able!to!more!than!meet!the!global!demand!with!
land!coverage!of!about!1%.
1
!!!Logically,!there!is!great!potential!and!reward!for!developing!
highly!efficient!solar!cells.!
Of!all!the!available!solar!technology,!traditional!silicon!solar!cells!are!the!most!well!
known!and!have!been!relatively!established!in!the!past!decades.!!!The!best!silicon!cells!have!
reach!more!than!20%!in!efficiency!and!have!been!commercialized!on!a!substantial!scale!
leading!to!the!solar!farms!and!residential!roof!top!installations!from!companies!such!as!
First!Solar!and!Solar!City.!!Other!inorganic!solar!cells!such!as!copper!indium!gallium!
diselenide,!and!cadmium!telluride!are!also!commercializing!and!accessible!to!the!business!
and!residential!sectors.!!Despite!its!ubiquity,!these!solar!cells!face!several!factors!hindering!
their!wide!spread!introduction!into!the!power!grid!system.!!The!cost!associated!the!
production!of!these!cells!often!render!the!resulting!price!of!power!uncompetitive!and!take!
a!long!period!of!time!to!recover!initial!investment.!!For!example,!crystalline!silicon!cells!
require!ultra/high!purity!crystals!of!silicon!obtained!from!energy/intensive!refining!of!
silicon.!!As!the!result,!electricity!from!coal!or!natural!gas!plants!is!often!a!fraction!of!the!cost!
of!solar!energy.!!Furthermore,!high!efficiency!multijunction!gallium!arsenide/based!cells!
are!only!economically!feasible!for!satellite!or!aerospace!use.!!Another!key!factor!in!the!
introduction!of!inorganic!cells!are!the!environmental!impacts.!!Cadmium!telluride!and!the!
emerging!lead!perovskite!contains!heavy!metal!elements!that!may!leak!into!the!
environment!once!decommissioned,!thus!residential!users!are!concerned!with!the!cost!of!
disposal!and!their!health.!!First!reported!in!1986!by!C.W.!Tang,!organic/based!solar!cells!or!
organic!photovoltaics!(OPVs)!have!earned!considerable!attention!in!the!last!decade!as!a!
! 5!
result!of!their!potential!to!be!low/cost,!lightweight,!flexible,!and!environmentally!friendly!
sources!of!energy.
1/5
!
!
1.2(Fundamentals(of(Organic(Photovoltaics(
The!structure!of!OPVs!makes!them!a!unique!alternative!to!conventional!solar!panels.!!
OPVs!are!built!on!transparent!substrates!(i.e.!glass!or!flexible!plastic),!and!contain!layers!of!
active!materials!that!are!submicron!in!thickness,!making!them!significantly!lighter!than!the!
traditional!heavier!solar!panels.!!Compared!to!the!low!absorptivity!of!inorganic!materials,!
Figure(1.1(Device(Architecture(and(Active(Layer(Structure(of(OPVs.(Shown!here!are!conventional!single!
junction!device!structure!(a)!and!multijunction!tandem!device!structure!(b).!!!Active!layer!can!either!be!lamellar!
such!as!the!planar!heterojunction!(c)!or!intimately!mixed!in!the!case!of!bulk!heterojunction!(d).!
! 6!
the!light!absorption!of!OPVs!are!not!compromised!as!a!thin!film.!!Nearly!all!of!the!active!
materials!are!high!absorptive!organic!dyes!or!industrial!pigments!such!as!perylene!
diimides,!phthalocyanines,!porphyrins,!benzothiadiazoles,!and!more.
3/6
!!As!shown!in!Figure!
1a,!the!general!structure!of!the!stack!consists!of!a!transparent!electrode,!Indium!Tin!Oxide!
(ITO),!active!layer!of!organic!absorbers,!and!a!reflective!metal!cathode.!!!The!active!layer!
can!be!derived!from!the!library!of!existing!organic!dye!molecules!and!polymers!that!show!
favorable!optical!and!electronic!properties.!!To!achieve!high!efficiencies,!the!organic!dyes!
must!have!high!absorptivity,!high!carrier!mobility,!and!complete!coverage!of!the!solar!
spectrum.
4,!6
!!While!polymeric!materials!are!common,!organic!small!molecules!are!also!
promising!candidates!for!solar!cells!because!they!can!be!modified!easily!to!consistently!
provide!these!ideal!properties.!!Given!these!advantages,!several!small/molecule!based!OPVs!
have!been!reported!with!power!conversion!efficiencies!(PCE)>8%.
6/9
!
Several!types!of!device!architecture!are!commonly!used!in!the!fabrication!of!OPVs.!!
The!conventional!planar!structure!(Fig.!1c)!is!easiest!to!fabricate!and!study!for!its!regular!
and!flat!structure,!however,!it!suffers!from!lower!PCE.!!The!widely!used!bulk!heterojunction!
(BHJ)!(Fig.!1d)!type!device!has!an!active!layer!of!mixed!donor/acceptor!material!with!
enhanced!surface!area.!!This!increase!in!surface!area!usually!leads!to!higher!PCE!from!
enhanced!photocurrent.!!!Tandem!solar!cells!(Fig.!1b)!are!often!used!to!increase!
photocurrent!by!stacking!two!or!three!individual!cells!to!cover!a!wider!absorption!profile.!!
These!devices!result!in!the!highest!efficiency,!but!are!the!most!difficult!to!study!and!
fabricate.!!They!require!substantial!amount!of!optimization!in!current!and!voltage!
matching!as!well!as!finding!conductive!materials!to!operate!in!a!thicker!device.!
! 7!
Figure!2!summarizes!the!key!steps!of!how!an!OPV!operates.!!1)!A!photon!can!be!
absorbed!by!either!component!(donor!or!acceptor)!of!the!active!layer,!forming!a!
coulumbically!bound!pair!of!electron!and!hole!called!the!exciton.!!2)!This!energetic!species!
migrates!in!the!film!until!it!reaches!the!donor/acceptor!(D/A)!interface,!where!3)!it!forms!a!
charge/transfer!(CT)!state!when!the!excited!electron!is!transferred!to!the!acceptor.!!This!
interface/localized!state!then!4)!charge!separates!into!free!carriers!that!are!collected!at!the!
electrodes.!!Each!step!of!the!process!is!crucial!and!can!affect!the!PCE!of!the!whole!device.!!!
The!power!conversion!efficiency!(!)!of!an!OPV!is!determined!by!the!following!
equation:!
!=
!
!"
!×!!
!"
!×!!!
!
!"#
!
,where!JSC!is!the!short/circuit!current,!VOC!is!the!open/circuit!voltage,!FF!is!the!fill!factor,!and!
Pinc!is!the!incident!power!from!the!light!source.!!!With!the!exception!of!Pinc,!each!of!these!
Figure(1.2(Charge(Generation(Process(in(OPV.!!The!steps!for!power!generation!are!summarized!in!the!4!
steps!with!solid!dots!as!electrons!and!empty!circles!as!holes.!!1)!A!photon!is!absorbed!by!the!active!material!
forming!a!bound!exciton.!!2)!The!exciton!migrates!to!the!!D/A!interface!before!it!recombines.!!3)!!The!charge/
transfer!is!formed!when!the!electron!is!donated!to!the!acceptor!molecule!forming!the!charged!interfacial!state.!!!
4)!Charge!separation!of!the!exciton!into!free!carriers!occurs!and!is!collected!at!the!electrodes.!
! 8!
parameter!is!influenced!by!the!excitation!process!previously!described.!!Figure!3!
represents!generic!current/density!versus!voltage!plot!collected!and!indicates!where!the!
values!for!the!parameters!can!be!obtained.!!The!maximum!power!point!lies!between!the!
values!of!JSC!and!VOC!and!is!determined!by!the!rectangularity!of!the!curve,!indicated!by!the!
fill!factor.!!!By!modifying!the!materials!used,!one!can!improve!the!efficiency!of!some!or!all!
the!processes!associated!with!their!corresponding!material!properties.!
!
1.3(Challenges(in(Organic(Photovoltaics(
The!JSC!is!limited!by!the!net!amount!of!photons!absorbed,!the!efficiency!of!carrier!
generation,!and!the!conductivity!of!the!film.!!One!effective!strategy!to!improve!the!JSC!is!by!
increasing!the!amount!of!visible!and!near/infrared!(NIR)!photons!harvested.!!While!many!
!
Figure(1.3(CurrentGDensity(Versus(Voltage(Plot(for(a(Typical(OPV(Device.(!A!typical!current/
density!versus!voltage!plot!is!shown!here!with!JSC,!VOC,!and!maximum!power!point!highlighted.!!The!fill!
factor!is!a!ratio!of!the!rectangles!inside!and!outside!of!the!curve.!!
! 9!
OPV!materials!have!strong!absorption!in!the!visible!region,!a!relatively!smaller!library!of!
materials!takes!advantage!of!the!NIR!photons.!!As!shown!in!Figure!4,!the!NIR!region!
contains!nearly!the!same!amounts!of!photons!are!available!in!the!visible!region.!!Accessing!
this!under!utilized!region!can!be!achieved!through!incorporating!either!a!pair!or!multiple!
dyes!with!complementary!absorption!in!a!blend!or!tandem!device,!respectively.!!By!taking!
advantage!the!solar!energy!available,!a!higher!Jsc!can!be!obtained!by!focusing!on!all!
optically!dense!regions!through!intelligent!chemical!design!and!synthesis.!!Another!
approach!to!increase!carrier!generation!is!to!alter!the!morphology!of!the!active!layer.!!This!
is!generally!achieved!through!the!incorporation!of!the!BHJ!structure.!!The!increased!surface!
area!minimizes!the!diffusion!distance!the!exciton!needs!to!travel!before!recombination,!
thus!maximize!the!number!of!excitons!that!are!able!to!charge!separate.!!!The!conductivity!
of!the!device!can!be!improved!by!modify!and!analyzing!the!morphology!of!the!entire!
device.!!With!proper!and!favorable!packing!of!the!molecules,!loss!from!recombination!at!
trap!sites!will!be!reduced,!leading!to!higher!overall!current.!
!!!!!!!!!!!!!!!!!! !
Figure(1.4(Visible(and(NIR(regions(of(Solar(Flux(and(Energetic(Gap(Between(Materials.(!The!
definition!of!ΔEDA!is!graphically!presented!here!as!the!difference!between!the!LUMOacceptor!and!
HOMOdonor.!
! 10!
The!material!pair!chosen!as!donor!and!acceptor!governs!the!VOC!of!devices.!!It!is!
understood!that!VOC!is!related!to!ΔEDA,!the!gap!between!the!lowest!unoccupied!molecular!
orbital!(LUMO)!of!the!acceptor!and!highest!occupied!molecular!orbital!(HOMO)!of!the!
donor,!shown!in!Figure!4.
10
!!ΔEDA!acts!as!the!thermodynamic!upper!limit!of!obtainable!
voltage!though!experimental!values!are!often!substantially!lower.!!The!lowered!value!is!a!
consequence!of!the!kinetic!interaction!charge!generation!and!recombination.!!The!
intermolecular!interaction!and!electronic!coupling!between!the!molecules!affects!this!
kinetic!factor!and!has!been!previous!studied!for!a!variety!of!materials.!
10/12
!!The!following!
equation!summarizes!the!relationship!between!VOC!and!the!thermodynamic!and!kinetic!
parameters:!
!
!"
=
!"#
!
!"
!
!"
!
!"
+ !
∆!
!"
2!
!
,!where!JSO!is!the!dark!current!and!the!term!JSC/JSO!indicates!the!extent!of!electronic!
coupling!between!the!molecules.!!Thus,!to!improve!VOC,!it!may!be!favorable!to!select!
material!pairs!that!have!an!intrinsically!high!ΔEDA.!!However,!it!does!not!guarantee!a!high!
VOC,!because!the!intermolecular!kinetic!interactions!may!result!in!a!high!dark!current,!
lowering!the!experimental!VOC.!!While!ΔEDA,!can!be!determined!through!cyclic!
voltammetry,!it!is!relatively!more!difficult!to!control!the!interaction!between!the!donor!and!
acceptor!though!molecular!bulk!and!orientation!have!been!shown!to!play!an!important!
role.
11/12
!
! With!a!value!between!0!and!1,!the!fill!factor!highlights!the!charge!collection!
efficiency!of!the!photovoltaic!device.!!It!is!the!quotient!of!the!maximum!obtainable!power!to!
the!product!of!the!JSC!and!VOC.!!A!value!close!to!1!is!desirable!as!it!suggests!that!the!device!
! 11!
has!high!carrier!mobility!and!no!significant!resistivity!or!recombination!sites!exist!within!
the!film.!!External!factors!that!can!influence!the!quality!of!the!devices!include!the!purity!of!
the!materials!(organics,!metals,!etc.)!used,!morphological!structure!of!the!films,!and!the!
inherent!electronic!properties!of!the!active!layer.!!Much!like!the!VOC,!predicting!the!exact!
experimental!fill!factor!a!priori!is!difficult,!however,!by!ensuring!the!quality!of!the!materials!
used!and!optimizing!deposition!conditions,!it!is!possible!to!maximize!fill!factor.!
!
1.4(Presented(Research(
In!the!following!chapters!(Scheme!1),!several!strategies!are!employed!to!improve!the!PCE!
of!OPVs!in!one!way!or!another.!!In!chapter!2,!Boron!Dipyrromethene!(BODIPY)!dyes!are!
synthesized!to!better!match!the!profile!of!the!solar!flux!by!shifting!their!absorption!
!
!
Scheme(1.1(A(Summary(of(BODIPY(Strategies(and(Modifications(Presented.(
! 12!
towards!lower!energy.!!The!properties!of!the!BODIPY!derivatives!are!examined!and!the!
origins!of!their!differences!are!discussed.!!In!chapter!3,!the!selected!BODIPY!dye,!bDIP,!is!
used!as!an!electron!donor!in!an!OPV.!!A!variety!of!device!structures!are!investigated,!and!
the!resulting!performance!are!summarized!and!discussed.!!It!was!found!that!spontaneous!
mixing!of!the!materials!at!the!interface!improved!the!PCE!substantially.!!In!chapter!4,!a!
BODIPY!dye!with!electron/withdrawing!groups,!cDIP,!is!studied!both!as!acceptor!and!a!
sensitizer!for!C60.!!!cDIP’s!intense!absorption!band!shows!efficient!energy!transfer!to!the!C60!
acceptor,!enabling!a!broader!spectral!coverage.!!In!chapter!5,!an!additional!family!of!π–
extended!BODIPY!dyes!was!synthesized,!further!shifting!the!absorption!toward!the!near/
infrared.!!Finally,!in!chapter!6,!progress!towards!synthesizing!BODIPY!dimers!to!improve!
VOC!through!symmetry!breaking!charge!transfer!is!presented.!
!
!
! !
! 13!
References(
!
(1)! Darling,!S.!B.;!You,!F.!The!case!for!organic!photovoltaics.!RSC$Advances$2013,!3,!
17633/17648.!
(2)! Tang,!C.!W.!Two/layer!organic!photovoltaic!cell.!Appl.$Phys.$Lett.$1986,!48,!183/185.!
(3)! Chen,!Y.;!Wan,!X.;!Long,!G.!High!Performance!Photovoltaic!Applications!Using!
Solution/Processed!Small!Molecules.!Acc.$Chem.$Res.$2013.!
(4)! Hains,!A.!W.;!Liang,!Z.;!Woodhouse,!M.!A.;!Gregg,!B.!A.!Molecular!Semiconductors!in!
Organic!Photovoltaic!Cells.!Chem.$Rev.$2010,!110,!6689/6735.!
(5)! Mishra,!A.;!Bäuerle,!P.!Small!Molecule!Organic!Semiconductors!on!the!Move:!
Promises!for!Future!Solar!Energy!Technology.!Angew.$Chem.,$Int.$Ed.$2012,!51,!2020/
2067.!
(6)! Lin,!Y.;!Li,!Y.;!Zhan,!X.!Small!molecule!semiconductors!for!high/efficiency!organic!
photovoltaics.!Chem.$Soc.$Rev.$2012,!41,!4245/4272.!
(7)! Zhou,!J.;!Zuo,!Y.;!Wan,!X.;!Long,!G.;!Zhang,!Q.;!Ni,!W.;!Liu,!Y.;!Li,!Z.;!He,!G.;!Li,!C.;!Kan,!B.;!
Li,!M.;!Chen,!Y.!Solution/Processed!and!High/Performance!Organic!Solar!Cells!Using!
Small!Molecules!with!a!Benzodithiophene!Unit.!J.$Am.$Chem.$Soc.$2013,!135,!8484/
8487.!
(8)! Kyaw,!A.!K.!K.;!Wang,!D.!H.;!Gupta,!V.;!Leong,!W.!L.;!Ke,!L.;!Bazan,!G.!C.;!Heeger,!A.!J.!
Intensity!Dependence!of!Current–Voltage!Characteristics!and!Recombination!in!
High/Efficiency!Solution/Processed!Small/Molecule!Solar!Cells.!ACS$Nano$2013,!7,!
4569/4577.!
(9)! Cnops,!K.;!Rand,!B.!P.;!Cheyns,!D.;!Verreet,!B.;!Empl,!M.!A.;!Heremans,!P.!8.4%!
efficient!fullerene/free!organic!solar!cells!exploiting!long/range!exciton!energy!
transfer.!Nat$Commun$2014,!5,!1/6.!
(10)! Schlenker,!C.!W.;!Thompson,!M.!E.!The!molecular!nature!of!photovoltage!losses!in!
organic!solar!cells.!Chem.$Commun.$2011,!47,!3702/3716.!
(11)! Erwin,!P.;!Thompson,!M.!E.!Elucidating!the!interplay!between!dark!current!coupling!
and!open!circuit!voltage!in!organic!photovoltaics.!Appl.$Phys.$Lett.$2011,!98,!/.!
(12)! Perez,!M.!D.;!Borek,!C.;!Forrest,!S.!R.;!Thompson,!M.!E.!Molecular!and!Morphological!
Influences!on!the!Open!Circuit!Voltages!of!Organic!Photovoltaic!Devices.!J.$Am.$Chem.$
Soc.$2009,!131,!9281/9286.!
!
( (
! 14!
Chapter(2.((
Impact(of(π-extension(on(BODIPY(Dyes(
2.1(Introduction(
Boron!dipyrromethenes,!or!BODIPY,!are!a!class!of!dyes!well!suited!to!strategy!for!
use!in!Organic!Photovoltaic!(OPV).!!The!high!optical!density!and!efficient!luminescence!
observed!for!BODIPYs!make!them!ideal!for!a!wide!range!of!applications,
1/3
!including!
biological!labeling!agents,!chemical!sensors,!laser!dyes,!and!solar!energy.!!One!effective!
strategy!to!improve!the!PCE!is!by!increasing!the!amount!of!visible!and!near/infrared!(NIR)!
photons!harvested.!!Since!a!substantial!portion!of!the!solar!flux!lies!in!the!red!and!NIR!
region,!a!higher!short/circuit!current!(Jsc)!can!be!obtained!by!focusing!on!these!optically!
dense!regions,!leading!to!a!device!with!higher!PCE.!!!By!extending!the!conjugated!π/system!
of!BODIPY!dyes,!a!shift!in!absorption!profile!can!be!achieved!leading!to!better!overlap!with!
the!solar!flux.!!!!In!this!chapter,!we!investigate!the!synthesis!and!photophysical!properties!
of!benzannulated!BODIPY!isomers,!bDIP!and!iDIP.!and!present!a!discussion!to!correlate!the!
differences!observed!from!the!site!of!ring!fusion.!!
(
2.2(Synthesis(of(bDIP(and(bDIPGc(
The!straightforward!synthesis!of!bDIP!was!first!reported!by!Ono!and!coworkers!via!
routes!outlined!in!Scheme!1.
4
!!The!bicyclic!isoindole!(1)!was!envisioned!as!the!ideal!
building!block!for!it’s!stability!and!reactivity.!!The!electron/withdrawing!carboxylic!ester!
moiety!prevents!the!oxidation!of!the!isoindole!under!ambient!conditions.!!!It!has!been!
shown!that!the!bicyclic!moiety!is!needed!because!the!reactivity!of!a!pyrrole!more!favorable!
! 15!
than!the!fully!conjugated!isoindole.
4
!!The!first!couple!steps!begins!with!a!Friedel/Craft!type!
reaction!in!appending!a!trimethyl/silyl!group!of!the!starting!alkyne!with!a!tosyl!group!
!
Scheme(2.1(Synthesis(of(bDIP(and(bDIPGc.!!
! 16!
followed!by!a!mild!basic!deproctection!of!the!second!to!yield!a!peach!color!solid.!!The!
modified!alkyne!undergoes!a!Diels/Alder!reaction!with!1,3/cyclohexadiene!to!form!the!
bicyclic!intermediate.!!The!oily!intermediate!was!used!without!purification!for!the!next!step!
in!which!1!is!formed!via!the!Barton/Zard!pyrrole!synthesis.!!A!major!yellow!impurity!is!
always!observed!in!the!last!step,!but!can!be!easily!removed!via!column!chromatography!to!
yield!white!needles!of!the!product!after!recrystallization.!!Overall,!the!synthesis!of!the!
isoindole!is!very!scalable,!with!expected!multi/gram!scale!yields!when!starting!with!25!g!of!
the!alkyne.!!
Deprotection!of!the!1!is!achieved!via!reduction!of!the!carboxylate!ester!with!lithium!
aluminum!hydride.!!Once!deprotected,!the!isoindole!is!sensitize!to!oxygen!and!readily!turns!
brown!over!a!period!of!15!minutes.!!Due!to!the!reactive!nature!of!the!1,!it!is!used!
immediately!upon!solvent!removal!and!without!any!further!purification.!!Over!2!steps!in!a!
single!pot!synthesis,!the!retro/Diels/Alder!BODIPY!(RDA!bDIP)!is!obtained!under!standard!
BODIPY!conditions!in!dilute!concentrations.!!The!purified!RDA/bDIP!crystals!can!be!fully!
converted!into!bDIP!via!thermal!treatment!at!180!°C!under!vacuum!with!the!expulsion!of!
the!ethylene!bridges.!
It!should!be!noted!that!another!method!to!bDIP!can!be!achieved!without!the!thermal!
step!to!deprotect!the!BODIPY!rings!via!dihydro/isoindole!(2).
5
!!In!this!alternate!route,!the!
bDIP!can!be!directly!synthesized!in!one!pot!with!a!higher!equivalence!of!dichloro/dicyano/
benzoquinone!(DDQ)!as!the!oxidant.!!However,!a!higher!loading!of!DDQ!has!been!shown!to!
lower!product!yield.
5
!!Furthermore,!the!synthesis!of!key!intermediate!2!also!requires!the!
condensation!of!gaseous!1,3/butadiene,!which!is!less!desirable!than!cyclohexadiene!as!a!
liquid.!
! 17!
Nonetheless,!bDIP/c!was!obtained!via!2!with!3!equivalence!of!DDQ.!!During!the!
initial!condensation!step!with!benzaldehyde!and!trifluoroacetic!acid!(TFA),!no!conversion!
product!was!observed!under!room!temperature!for!over!5!hours,!which!typically!results!in!
the!full!consumption!of!the!aldehyde.!!The!inactivity!is!primarily!due!to!the!presence!of!the!
carboxylate!ester!group.!!The!electron/withdrawing!nature!of!the!carboxylate!esters!
deactivates!the!nucleophilicity!of!the!pyrrole!at!the!α/position,!preventing!the!
condensation!reaction!to!proceed.!!Upon!refluxing!the!reaction!mixture!in!dichloromethane!
overnight,!the!activation!barrier!is!resolved!with!the!additional!energy.!!The!consumption!
of!the!benzaldehyde!was!confirmed!by!TLC!leading!to!the!subsequent!product,!bDIP/c,!in!
moderate!yields!(29%)!after!purification!by!flash!chromatography.!!!
!
2.3(Synthesis(of(iDIP(
( Initial!efforts!in!accessing!the!iDIP!moiety!with!benzene!fusion!at!the!other!pyrrole!
position!focused!on!the!synthesis!of!the!analogous!RDA/type!indole!(3)!as!depicted!in!
Method!A.!in!Scheme!2.!!The!RDA!scaffold!can!be!achieved!via!a!Diels/Alder!reaction!with!
chloroacrylonitrile!and!1,3/cyclohexadiene!as!the!dienophile!and!dien,!respectively.
6
!!The!
crude!intermediate!was!then!treated!with!KOH!without!further!purification!resulting!in!the!
desired!bicyclic!ketone!in!low!yields.!!While!literature!reports!25%!over!these!two!steps,!a!
9%!yield!was!obtained!primarily!due!to!the!large!amount!of!side!products!observed.!!While!
the!oxime!intermediate!in!the!following!step!can!be!obtained!in!90%!yield!via!treatment!
with!hydroxylamine!hydrochloride,!the!final!cyclization!of!the!oxime!to!indole!was!difficult!
to!achieve.!!!Though!a!library!of!π–extended!indoles!had!been!previously!synthesized!by!
bubbling!acetylene!gas!in!the!presence!of!LiOH,!attempts!to!synthesize!the!3!was!
! 18!
unsuccessful.
7/8
!!The!acetylene!gas!was!passed!through!concentrated!sulfuric!acid!to!
remove!any!moisture!prior!to!the!introduction!to!the!reaction!vessel.!!Despite!multiple!
attempts!under!different!conditions!of!temperature!and!acetylene!pressure,!no!desired!
oxime!was!detected!from!the!reaction!mixture!after!workup.!
! Due!to!the!unsuccessful!attempts!with!Method!A.,!Method!B.!was!employed!using!
commercially!available!3/methylindole!(4).!!!!In!a!typical!acid/catalyzed!condensation!
Scheme(2.2(Synthesis(of(iDIP.!!Only!Method!B!was!successful!in!yielding!desired!product.!
!
Oxidant( Temperature( Reaction(time( Improvement( (
DDQ# 25#°C# 15#h# No# #
DDQ# 25#°C# 2#h# No# #
DDQ# 0#°C# 2#h# Slight# #
p1chloranil# 25#°C# 2#h# No# #
(
Table(2.1!Optimization(Conditions(for(iDIP(Synthesis.!!No!significant!improvement!for!reaction!yield!was!
observed.!
! 19!
reaction,!4!was!converted!to!the!corresponding!dipyrromethane!in!high!yields.
9
!
Surprisingly,!iDIP!was!obtained!following!reaction!under!standard!BODIPY!conditions.!!The!
product!was!not!brightly!fluorescent!in!solution!as!expected,!but!NMR!and!crystallographic!
data!confirms!the!identity!of!the!desired!product.!!Initial!yields!were!low!and!conditions!to!
examine!whether!the!oxidation!step!or!borylation!step!was!the!yield/limiting!step!are!
summarized!in!Table!1.!!!Despite!these!efforts,!a!significant!amount!of!poorly!soluble!deep!
purple!by/product!is!always!formed!at!the!end!of!the!reaction.!!Additional!trials!to!optimize!
the!reaction!yield!by!reducing!the!pyrrole!concentration!and!reaction!time!were!
unsuccessful.!!Ultimately,!the!low!yield!of!the!reaction!may!be!primarily!due!to!the!inherent!
reactivity!of!the!indole!moiety!when!compared!to!the!RDA/isoindole!building!block!of!bDIP!
that!preserves!the!reactivity!of!the!pyrrole!unit.!!With!the!starting!materials!commercially!
available,!further!attempts!to!optimize!the!yield!were!not!pursued.!
(
2.4(Material(Properties(of(bDIP(and(iDIP(
Depending!on!the!site!of!the!benzannulation,!the!resulting!properties!(Table!2.)!of!
the!molecules!differ!significantly.!!As!expected,!the!extended!π/system!from!the!fusion!of!
the!benzene!rings!leads!to!a!narrowing!of!the!band!gap,!and!ultimately!a!broader!
absorption!in!the!red!region!of!the!solar!spectrum!than!the!parent!BODIPY!compounds!as!
seen!in!Figure!1.!!!The!solution!absorption!maxima!of!the!BODIPYs!shift!from!500!nm!for!
the!parent!compound!!to!602!nm!and!560!nm!for!bDIP!and!iDIP,!respectively.
4
!!!While!bDIP!
has!a!strong!photoluminescence!quantum!yield!of!0.84,!no!emission!from!iDIP!can!be!
observed!interestingly.!!Furthermore,!the!extinction!coefficient!for!bDIP!(10
5!
M
/1
cm
/1
)!is!
one!order!of!magnitude!greater!than!iDIP!(10
4!
M
/1
cm
/1
).!
! 20!
!
!
Figure(2.1(Absorption(Spectra(and(Chemical(Structures(of(RDAGbDIP,(bDIP,(and(iDIP.!Solution!absorption!plot!of!
BODIPY!derivations!in!dichloromethane.!!
!!
λ
abs
a
(
(nm)( λ
em
a
(
(nm)(
εsol
a
((
((x(10
4
(M
=1
cm
=1
)
Φ
a
( E
red
b
((V)( E
ox
b
((V)( HOMO((eV)( LUMO((eV)(
bDIP# 602# 610# 37.2# 0.84# 11.7# 0.4# 2.75# 5.15#
iDIP# 560# 1# 6.8# 1# 11.04# 0.98# 3.54# 5.97#
!
Table(2.2(Physical(Properties(of(bDIP(and(iDIP.!!
a
Values!measured!in!methylene!chloride.!!
b
Versus!ferrocene/!
ferrocenium.!
!
!
Figure(2.2!Crystal(and(Packing(Structures(of(bDIP(and(iDIP.!Crystal!structure!of!bDIP!(a)!and!iDIP!(b).!!Packing!
structure!of!bDIP!(c)!and!iDIP!(d).!
!
! 21!
The!crystal!structure!of!iDIP!has!not!been!reported!before!and!is!shown!in!Figure!2.!!!
Intermolecular!interactions!are!seen!in!the!crystal!packing!of!both!bDIP!and!iDIP.!!bDIP!
shows!significant!overlap!of!the!benzannulated!rings!of!adjacent!molecules!with!a!π/to/π!
spacing!of!3.45!Å,!while!iDIP!displays!a!herring/bone!type!of!packing!with!minimum!
distance!between!the!rings!to!be!4.18!Å.
4
!!The!structural!differences!in!the!site!of!ring!
fusion!affects!the!way!that!both!isomers!pack!significantly!and!the!degree!of!π/to/π!!
interaction.!!
Reversible!oxidation!and!reduction!waves!for!both!compounds!were!observed!in!the!
cyclic!voltammograms.!!The!potentials!for!bDIP!are!0.395!V!and!/1.70!V!versus!ferrocene,!
for!the!oxidation!and!reduction,!respectively,!and!consistent!with!reported!values.
4
!For!
iDIP,!the!corresponding!values!are!0.98!V!and!/1.04!V.!!The!highest!occupied!molecular!
orbital!(HOMO)!and!lowest!unoccupied!molecular!orbital!(LUMO)!were!calculated!using!
reported!methods
10/11
!and!are!shown!in!Figure!3,!relative!to!C60.
12
!!These!energy!level!
alignments!of!bDIP!and!iDIP!are!suitable!to!be!coupled!with!C60!as!the!electron!donor!in!an!
OPV.!!!Compared!with!bDIP,!iDIP!has!much!deeper!LUMO!and!HOMO!levels,!which!can!
result!in!higher!device!voltage!with!a!wider!gap!between!LUMOAcceptor!and!HOMODonor.!!
!
Figure(2.3(Calculated(Energies(and(Cyclic(Voltammograms(of(bDIP(and(iDIP.!!Calculated!HOMO!and!
LUMO!of!C60,!iDIP,!and!bDIP!.!!Cyclic!voltammograms!of!iDIP!(left)!and!bDIP!(right).!
! 22!
However,!iDIP!seems!to!have!a!detrimental!deactivation!pathway!due!to!its!lack!of!
fluorescence.!!Compounding!this!with!the!synthetic!ease!of!bDIP,!photovoltaic!devices!
based!on!bDIP!were!the!focus!of!further!studies!in!Chapter!3.!
(
2.5(Impact(of(Fusion(Mode(on(Photophysical(Property(
! The!disparity!between!the!molecular!orbitals!of!the!two!benzene/fused!isomers!are!
the!origin!of!the!marked!difference!in!their!photophysical!properties.!!Works!previously!
reporting!related(derivatives!have!only!noted!the!deviation!of!iDIP/type!molecules’!
properties!from!typical!BODIPY!observations!and!stating!experimental!results.!
13/14
!!!To!
date,!a!comprehensive!discussion!on!examining!the!origin!to!these!differences!is!still!
lacking.!!By!repeating!the!same!exercise!reported!by!Hanson!et.$al.$for!several!conjugated!
organic!systems,!!the!effect!of!benzannulation!on!the!BODIPY!core!can!be!clearly!
explained.
15
!!In!their!work,!they!concluded!that!π–extension!does!not!always!lead!to!the!
narrowing!of!the!band!gap!(i.e.,!the!destabilization!and!stabilization!of!the!HOMO!and!
LUMO,!respectively).!!In!fact,!the!net!effect!on!the!band!gap!depends!entirely!on!the!
interaction!between!the!molecular!orbitals!of!parent!compound!and!the!1,3/butadiene!
fragment!that!forms!the!new!π!system.!!This!interaction!can!be!further!simplified!into!
symmetry!and!energetics!compatibility.!!In!the!case!of!BODIPY,!benzannulation!on!both!
isomers!lead!to!different!degree!of!red/shift!from!the!narrowing!of!the!HOMO/LUMO!gap.!
For!bDIP!in!Figure!4,!the!butadiene!HOMO!has!the!correct!symmetry!to!interact!with!
both!the!HOMO!and!LUMO!of!the!BODIPY!core!while!the!butadiene!LUMO!lacks!the!
compatible!phase.!!!The!interaction!results!in!the!destabilization!of!both!the!BODIPY!HOMO!
and!LUMO,!with!a!net!reduction!in!the!band!gap,!hence!the!redder!absorption!maximum.!!
Similarly!in!iDIP,!only!the!butadiene!LUMO!is!of!the!correct!symmetry!to!interact!with!the!
! 23!
BODIPY!in!the!corresponding!position.!!The!final!results!in!Figure!4!highlight!the!difference!
!
!
!
!
!
Figure(2.4(Molecular(Interaction(Between(BODIPY(Core(and(Butadiene(Fragment.!!The!molecular!
interactions!between!BODIPY!core!and!butadiene!fragment!to!form!bDIP!(top)!and!iDIP!(bottom).!
! 24!
in!the!stabilization!and!destabilization!of!the!BODIPY!orbitals.!!In!the!iDIP!case,!the!BODIPY!
LUMO!is!stabilized!instead!while!the!BODIPY!and!butadiene!HOMOs!seem!to!be!
destabilized!to!higher!energies.!!!It!is!should!be!noted!that!while!the!calculated!iDIP!HOMO!
is!destabilized,!the!expected!trend!should!be!a!stabilizing!interaction!for!the!iDIP!HOMO!
between!the!BODIPY!and!butadiene!fragment.!!This!contradiction!will!be!examined!further!
in!the!next!paragraphs.!!Despite!the!difference,!the!net!effect!is!still!a!narrowing!of!the!
HOMO/LUMO!gap!compared!to!the!parent!BODIPY.!!This!preliminary!picture!presents!
simple!explanation!to!the!difference!in!red!shifting!of!absorption!maxima!as!well!as!
matching!the!redox!trend!observed!from!electrochemistry.!
BODIPYs!commonly!exhibit!a!strong!narrow!absorption!as!observed!for!bDIP.!!
However,!iDIP’s!broad!and!featureless!absorption!profile!is!an!odd!exception.!!To!elucidate!
the!origin!of!the!broadness!in!iDIP!absorption,!it!is!necessary!to!examine!the!underlying!
molecular!orbitals!and!the!excited!states.!!!For!bDIP,!the!calculated!data!in!Table!3!show!a!
single!transition!at!479!nm!with!an!oscillator!strength!of!0.7!and!strong!transition!dipole!
moment!along!the!long!axis!of!the!molecule!at!8.48.!!Though!there!is!a!clear!discrepancy!for!
calculated!energies!versus!experimental!values,!it!has!been!reported!that!the!trends!
obtained!from!TD/DFT!are!consistent!with!measured!results!for!a!variety!of!values.
16
!!
These!results!clearly!reflect!the!single!narrow!absorption!peak!observed.!!Unlike!bDIP,!
three!excited!states!were!obtained!for!iDIP!with!energies!of!605!nm,!564!nm,!and!459!nm!
as!summarized!in!Table!3!!Both!lower!energy!transitions,!S1!and!S2,!have!relatively!weaker!
oscillator!strength!and!transition!dipole!moments!when!compared!to!the!S3.!!From!this,!we!
would!already!expect!a!broader!absorption!profile!for!iDIP!from!bDIP.!!Additionally,!the!
strongest!transition,!S3,!is!higher!energy!than!bDIP’s!main!transition,!thus!offering!some!
! 25!
insight!to!the!relatively!bluer!position!of!the!measured!absorption!maxima!between!iDIP!
and!bDIP!at!555!nm!and!602!nm,!respectively.!
The!calculated!models!show!that!the!HOMO!and!HOMO(/2)!participate!in!the!S1!and!
bDIP(
Transition( X(coefficient( λ
max(
(nm)(
Transition(Dipole
a
(
(debye)(
Oscillator(
Strength(
S
1
# HOMO#to#LUMO# 1.00# 479# 8.48# 0.7#
# # # # # #
iDIP( (( (( (( ((
S
1
#
HOMO#to#LUMO# 10.73#
605# 1.58# 0.01#
HOMO12#to#LUMO# 10.67#
# # # # # #
S
2
# HOMO11#to#LUMO# 10.99# 564# 1.06*# 0.01#
# # # # # #
S
3
#
HOMO#to#LUMO# 10.68#
459# 9.82# 0.99#
HOMO12#to#LUMO# 10.75#
Table(2.3(Computational(Outputs(for(bDIP(and(iDIP.!Calculated!excited!state!energies!for!bDIP!and!iDIP.!!
a
Listed!dipole!moments!all!oriented!in!the!y/axis!(long!axis)!of!the!molecule!with!the!exception!of!the!*!entry!
which!is!oriented!with!respect!to!the!z/axis.!
!
!
!
!
Figure(2.5(Molecular(Orbitals(of(BODIPY,(bDIP,(and(iDIP.!Calculated!molecular!orbitals!of!bDIP!and!iDIP!
with!their!corresponding!symmetry!assignments.!
! 26!
S3!transitions.!!Compared!to!bDIP,!these!frontier!orbitals!are!energetically!close,!with!
HOMO(/1)!and!HOMO(/2)!being!identical!in!energy.!!!In!addition,!the!difference!between!
HOMO!and!HOMO(/1)!for!iDIP!is!substantially!smaller!at!0.33!eV!than!for!bDIP!at!1.62!eV.!!
The!proximity!of!these!iDIP!orbitals!is!mainly!due!to!the!rearrange!of!the!BODIPY!frontier!
orbitals!upon!ring!fusion!as!depicted!in!Figure!5.!!Upon!a!more!detailed!examination,!the!
HOMO!(a2)!of!the!parent!BODIPY!is!actually!stabilized!resulting!in!a!deeper!iDIP!orbital!
(a2)!.!!Additionally,!two!deeper!BODIPY!MOs!are!destabilized!substantially!resulting!in!the!
new!HOMO!(a2)!and!HOMO(/1)!(b1).!!This!model!explains!the!existence!of!the!three!
transitions!given!the!proximity!of!the!energies!unobserved!in!bDIP!and!further!contributes!
to!the!difference!in!the!absorption!profile.!!
Upon!inspecting!the!electron!density!for!the!frontier!orbitals,!one!can!see!that!there!
is!significant!change!between!the!HOMOs!and!the!LUMO.!!!Compared!to!bDIP!where!the!
densities!are!localized!around!the!same!atoms!for!both!the!HOMO!and!LUMO,!the!iDIP!
orbitals!see!a!drastic!movement!of!electron!density.!!!It!can!be!inferred!that!due!to!these!
differences!in!electron!density,!the!wave!function!overlap!between!the!initial!and!final!
transition!states!are!lower!for!iDIP!than!bDIP.!!!From!this!observation,!we!can!expect!the!
Frank/Condon!factor!for!the!iDIP!to!be!smaller!than!bDIP,!and!will!have!larger!
reorganization!energy!between!the!transition!states.!!This!reorganization!energy!plays!a!
key!factor!in!the!broadening!of!the!iDIP!absorption!profile!predominantly!through!the!
accessing!additional!excited!state!vibronics!as!depicted!in!Figure!6.!!Ultimately,!this!leads!to!
lower!probability!in!the!main!S1!transitions,!a!lower!molar!absorptivity,!a!broad!featureless!
absorption!spectrum.!!!
!
!
! 27!
!
2.6(Conclusion(
! bDIP!and!iDIP!differ!only!by!the!site!of!ring!fusion,!but!their!properties!and!synthetic!
accessibility!are!significantly!different.!!bDIP!was!found!to!be!highly!absorptive!and!
emissive!with!sharp!spectral!profile,!while!iDIP!exhibited!no!fluorescence!with!a!broaden!
absorption!profile.!!!The!fusion!of!the!butadiene!fragment!on!to!the!BODIPY!core!alters!the!
electronic!structure!of!the!final!molecule!markedly!depending!on!the!position!of!
attachment.!!By!examining!the!interaction!between!the!fragments,!we!found!that!HOMO!
and!LUMO!levels!are!affected!differently!depending!on!which!of!the!butadiene!frontier!
orbitals!the!BODIPY!core!interacts!with.!!In!the!case!of!bDIP,!only!the!HOMO!and!LUMO!
!
Figure(2.6(Potential(Energy(Diagrams(for(bDIP(and(iDIP.!Potential!energy!diagram!showing!transition!
of!molecule!with!low!reorganizational!energy!and!a!sharp!absorption!spectrum!(a)!and!with!high!
reorganization!energy!with!a!broad!absorption!resulting!from!multiple!vibronic!transitions!(b).!
! 28!
were!destabilized!and!stabilized,!respectively;!leading!to!a!strong!red/shifted!transition!
with!electron!density!changes.!!For!iDIP,!deeper!BODIPY!molecular!orbitals!were!involved!
in!the!interaction!with!the!butadiene!LUMO,!leading!to!several!orbitals!with!similar!
energies.!!These!additional!transitions!and!the!large!reorganization!of!electron!density!in!
iDIP!leads!to!the!broad!spectrum!observed.!!This!unexpected!difference!highlights!the!
versatility!of!this!class!of!dyes,!and!encourages!further!studies!for!simple!systems!that!can!
lead!to!valuable!insights.!
!!
2.7(Experimental(
! Unless!noted!otherwise,!all!chemicals!were!purchased!from!Sigma/Aldrich!and!used!
without!further!purification.!!Dry!solvents!were!purified!using!a!Glass!Contour!Solvent!
System!and!all!reactions!were!performed!under!inert!nitrogen!atmosphere.!!bDIP!was!
prepared!as!reported!by!Ono!and!coworkers!starting!from!a!Retro/Diels/Alder!isoindole!
precursor!followed!by!a!standard!BODIPY!synthesis.
4,!17
!!The!resulting!bronze/colored!
solids!were!purified!by!recrystallization.!!iDIP!was!synthesized!following!modified!
procedure!to!yield!the!dipyrromethenes!followed!by!standard!BODIPY!conditions.
4,!9
!!NMR!
spectra!were!recorded!on!a!Varian!400!NMR!spectrometer!and!referenced!to!the!residual!
proton!resonance!of!chloroform!(CDCl3)!solvent!at!7.26!ppm.!
!
( (
! 29!
2.8(NMR(Spectra
(
NH
CO
2
Et
N N
B
F
2
! 30!

N N
B
F
2
N N
B
F
2 EtO
2
C CO
2
Et
! 31!

N N
B
F
2
! 32!
2.9 TD-DFT Calculations
Excitation!energies!and!molecular!orbitals!were!calculated!with!time/dependent!DFT!
(TDDFT)!using!the!B3LYP!functional!basis!set!with!a!Titan!software!package.!

2.10 Crystallography Details
A!metallic!dark!purple/green!prism/like!specimen!of!C28H25BF2N2,!approximate!dimensions!
0.21!mm!x!0.24!mm!x!0.32!mm,!was!used!for!the!X/ray!crystallographic!analysis.!
Instrument!description!The!X/ray!intensity!data!were!measured!on!a!Bruker!APEX!II!CCD!
system!equipped!with!a!TRIUMPH!curved/crystal!monochromator!and!a!Mo!fine/focus!tube!
(λ!=!0.71073!Å).!!A!total!of!2520!frames!were!collected.!The!total!exposure!time!was!3.50!
hours.!Integration!The!frames!were!integrated!with!the!Bruker!SAINT!software!package!
using!a!SAINT!V7.68A!algorithm.!The!integration!of!the!data!using!a!monoclinic!unit!cell!
yielded!a!total!of!52804!reflections!to!a!maximum!θ!angle!of!30.56°!(0.70!Å!resolution),!of!
which!6752!were!independent!(average!redundancy!7.820,!completeness!=!98.8%,!Rint!=!
3.35%,!Rsig!=!2.09%)!and!5473!(81.06%)!were!greater!than!2σ(F
2
).!Unit!cell!The!final!cell!
constants!of!a!=!8.6191(3)!Å,!b!=!12.4831(5)!Å,!c!=!20.8312(7)!Å,!β!=!95.7790(10)°,!volume!
=!2229.90(14)!Å
3
,!are!based!upon!the!refinement!of!the!XYZ/centroids!of!137!reflections!
above!20!σ(I)!with!5.954°!using!the!multi/scan!method!(SADABS).!The!ratio!of!minimum!to!maximum!apparent!
transmission!was!0.895.!!
!
Structure!solution!The!structure!was!solved!and!refined!using!the!Bruker!SHELXTL!
Software!Package,!using!the!space!group!P!1!21/n!1,!with!Z!=!4!for!the!formula!unit,!
! 33!
C28H25BF2N2.!Structure!refinement!The!final!anisotropic!full/matrix!least/squares!
refinement!on!F
2
!with!303!variables!converged!at!R1!=!4.04%,!for!the!observed!data!and!
wR2!=!11.44%!for!all!data.!The!goodness/of/fit!was!1.033.!The!largest!peak!in!the!final!
difference!electron!density!synthesis!was!0.421!e
/
/Å
3
!and!the!largest!hole!was!/0.250!e
/
/Å
3
!
with!an!RMS!deviation!of!0.050!e
/
/Å
3
.!On!the!basis!of!the!final!model,!the!calculated!density!
was!1.306!g/cm
3
!and!F(000),!920!e
/
.!
! !
! 34!
References(
!
(1)! Benstead,!M.;!Mehl,!G.!H.;!Boyle,!R.!W.!4,4 /Difluoro/4/bora/3a,4a/diaza/s/
indacenes!(BODIPYs)!as!components!of!novel!light!active!materials.!Tetrahedron$
2011,!67,!3573/3601.!
(2)! Ulrich,!G.;!Ziessel,!R.;!Harriman,!A.!The!Chemistry!of!Fluorescent!Bodipy!Dyes:!
Versatility!Unsurpassed.!Angew.$Chem.,$Int.$Ed.$2008,!47,!1184/1201.!
(3)! Loudet,!A.;!Burgess,!K.!BODIPY!Dyes!and!Their!Derivatives: !Syntheses!and!
Spectroscopic!Properties.!Chem.$Rev.$2007,!107,!4891/4932.!
(4)! Shen,!Z.;!Röhr,!H.;!Rurack,!K.;!Uno,!H.;!Spieles,!M.;!Schulz,!B.;!Reck,!G.;!Ono,!N.!Boron–
Diindomethene!(BDI)!Dyes!and!Their!Tetrahydrobicyclo!Precursors—en!Route!to!a!
New!Class!of!Highly!Emissive!Fluorophores!for!the!Red!Spectral!Range.!Chem.K Eur.$J.$
2004,!10,!4853/4871.!
(5)! Uppal,!T.;!Hu,!X.;!Fronczek,!F.!R.;!Maschek,!S.;!Bobadova/Parvanova,!P.;!Vicente,!M.!G.!
H.!Synthesis,!Computational!Modeling,!and!Properties!of!Benzo/Appended!BODIPYs.!
Chem.K Eur.$J.$2012,!18,!3893/3905.!
(6)! Claret,!F.;!Carrupt,!P./A.;!Vogel,!P.!Regioselective!Electrophilic!Additions!of!
Bicyclo[2.2.n]alk/2/enes!Controlled!by!Remote!Epoxide!Functions.!Helv.$Chim.$Acta$
1987,!70,!1886/1896.!
(7)! Kang,!D./J.!E.,!Da/Han;!Mo,!Jun/Tae;!Kim,!Hyun/Seok;!Sokkalingam,!Punidha;!Lee,!
Chang/Hee;!Lee,!Phil/Ho!Synthesis!of!BODIPY!Chromophores!Bearing!Fused/
Carbocycles.!Bull.$Korean$Chem.$Soc.$2010,!31,!507/510.!
(8)! Mikhaleva,!A.!I.;!Shmidt,!E.!Y.;!Protsuk,!N.!I.;!Zorina,!N.!V.;!Trofimov,!B.!A.!Effect!of!
alkali!metal!cations!on!the!synthesis!of!4,5,6,7/tetrahydroindole!and!its!vinyl!
derivative!from!cyclohexanone!oxime!and!acetylene!in!MOH/DMSO!systems.!Dokl.$
Chem.$2008,!423,!273/275.!
(9)! Nishiki,!M.;!Oi,!W.;!Ito,!K.!Anion!binding!properties!of!indolylmethanes.!J.$Inclusion$
Phenom.$Macrocyclic$Chem.$2008,!61,!61/69.!
(10)! D’Andrade,!B.!W.;!Datta,!S.;!Forrest,!S.!R.;!Djurovich,!P.;!Polikarpov,!E.;!Thompson,!M.!
E.!Relationship!between!the!ionization!and!oxidation!potentials!of!molecular!organic!
semiconductors.!Org.$Electron.$2005,!6,!11/20.!
(11)! Djurovich,!P.!I.;!Mayo,!E.!I.;!Forrest,!S.!R.;!Thompson,!M.!E.!Measurement!of!the!
lowest!unoccupied!molecular!orbital!energies!of!molecular!organic!semiconductors.!
Org.$Electron.$2009,!10,!515/520.!
(12)! Wilke,!A.;!Endres,!J.;!Hormann,!U.;!Niederhausen,!J.;!Schlesinger,!R.;!Frisch,!J.;!
Amsalem,!P.;!Wagner,!J.;!Gruber,!M.;!Opitz,!A.;!Vollmer,!A.;!Brutting,!W.;!Kahn,!A.;!
Koch,!N.!Correlation!between!interface!energetics!and!open!circuit!voltage!in!
organic!photovoltaic!cells.!Appl.$Phys.$Lett.$2012,!101,!233301/4.!
(13)! Ni,!Y.;!Zeng,!W.;!Huang,!K./W.;!Wu,!J.!Benzene/fused!BODIPYs:!synthesis!and!the!
impact!of!fusion!mode.!Chem.$Commun.$2013,!49,!1217/1219.!
(14)! Wakamiya,!A.;!Murakami,!T.;!Yamaguchi,!S.!Benzene/fused!BODIPY!and!fully/fused!
BODIPY!dimer:!impacts!of!the!ring/fusing!at!the!b!bond!in!the!BODIPY!skeleton.!
Chem.$Sci.$2013,!4,!1002/1007.!
! 35!
(15)! Hanson,!K.;!Roskop,!L.;!Djurovich,!P.!I.;!Zahariev,!F.;!Gordon,!M.!S.;!Thompson,!M.!E.!A!
Paradigm!for!Blue/!or!Red/Shifted!Absorption!of!Small!Molecules!Depending!on!the!
Site!of!π/Extension.!J.$Am.$Chem.$Soc.$2010,!132,!16247/16255.!
(16)! Momeni,!M.!R.;!Brown,!A.!Why!Do!TD/DFT!Excitation!Energies!of!BODIPY/Aza/
BODIPY!Families!Largely!Deviate!from!Experiment?!Answers!from!Electron!
Correlated!and!Multireference!Methods.!J.$Chem.$Theory$Comput.$2015,!11,!2619/
2632.!
(17)! Okujima,!T.;!Jin,!G.;!Hashimoto,!Y.;!Yamada,!H.;!Uno,!H.;!Ono,!N.!Synthesis!of!4,7/
Dihydro/2H/isoindole!Derivatives!via!Diels/Alder!Reaction!of!Tosylacetylene.!
Heterocycles$2006,!70,!619!/!626.!

! !
! 36!
Chapter(3.(
OPV(Application(of(Red(BODIPY(Dye,(bDIP(
3.1(Introduction(
Organic!small!molecules!are!promising!candidates!for!solar!cells!because!they!can!
be!modified!easily!to!provide!these!ideal!properties.!!Given!these!advantages,!small/
molecule!based!OPVs!have!been!reported!with!power!conversion!efficiencies!(PCE)>8%.
1/4
!!
bDIP!(Scheme!1)!discussed!in!Chapter!2.!is!well!suited!to!this!strategy!for!improving!OPV!
performance!through!modifying!the!parent!compound.!!The!high!optical!density!and!
efficient!luminescence!and!red/near/infrared!asborption!observed!for!bDIP!make!them!
ideal!for!solar!energy!applications.!!!Though!many!π/conjugated!red/NIR!BODIPYs!have!
been!reported
5/8
!in!the!literature,!only!a!handful!have!been!applied!to!photovoltaics,
9/13
!
including!a!BODIPY/based!bulk!heterojunction!(BHJ)!device!with!a!PCE!of!4.7%.
14
!!Here,!we!
investigate!bilayer!and!planar/mixed!heterojunction!(PMHJ)!device!architectures!
incorporating!bDIP!and!characterized!it’s!device!morphology!and!photovoltaic!properties.!
! !
Figure(3.1(Structure(of(Parent(BODIPY(and(bDIP(and(Solution(&(Thin(Film(Absorptions(and(Emissions(
of(bDIP.((Absorption!(solid!shapes)!and!emission!(hollow!shapes)!of!bDIP!taken!in!dichloromethane!solution!
and!thin!film!on!a!quartz!substrate.(
! 37!
!
3.2(Thin(Film(Properties(of(bDIP(
Photophysical!measurements!of!the!neat!thin!film!show!a!marked!bathochromic!
shift!of!the!absorption!maximum!to!640!nm!with!substantial!broadening!of!the!peak,!and!an!
absorption!coefficient!of!3.03!x!10
5!
cm
/1
!at!λmax.!!The!red!shift!and!broadening!relative!to!
solution!spectra!are!likely!the!result!of!strong!π/π!stacking!of!adjacent!molecules.!!Strong!
intermolecular!interactions!are!seen!in!the!crystal!packing!of!bDIP,!which!shows!significant!
overlap!of!the!benzannulated!rings!of!adjacent!bDIPs!with!a!π/to/π!spacing!of!3.45!Å.
15
!!The!
thin!film!sample!gives!a!large!Stokes!shift!of!the!emission!in!the!thin!film!at!680nm.!!As!
discussed!in!the!previous!chapter,!the!highest!occupied!molecular!orbital!(HOMO)!and!
lowest!unoccupied!molecular!orbital!(LUMO)!of!bDIP!were!calculated!using!reported!
methods
16/17
!and!are!shown!in!Figure2a,!relative!to!C60.
18
!!The!energy!level!alignment!of!
bDIP!makes!a!suitable!donor!to!be!coupled!with!C60!as!the!electron!acceptor!in!an!OPV.!
!
3.3(Bilayer(Photovoltaic(Devices!
Bilayer!OPVs!were!fabricated!with!the!structure:!ITO/bDIP!(10!–!110!nm)/$
C60!(40!nm)/!bathocuproine!(10!nm)/Al!(100!nm),!shown!in!Figure!2a.!!!The!current/
density!versus!voltage!plots!for!these!bDIP/based!OPVs!are!presented!in!Figure!2b!and!the!
relevant!parameters!are!summarized!graphically!in!Figure!3.!!Excluding!the!10nm!device,!
the!open/circuit!voltage!(Voc)!observed!for!bDIP/C60!devices!are!high,!falling!between!
0.74!V!and!0.81!V.!!The!Jsc!improves!with!increasing!thicknesses!of!the!bDIP!donor!layer,!
starting!from!3.9!mA/cm
2
!at!bDIP!=!10!nm!to!a!maximum!current!of!8.7!mA/cm
2!
for!the!
70!nm!bDIP!device.!The!performance!of!OPVs!with!bDIP!donor!layer!thicknesses!of!10/40!
! 38!
nm,!poor!performing!devices!were!observed,!due!principally!to!low!fill!factor!(FF).!!The!10!
nm!donor!layer!gives!a!very!low!VOC!and!FF,!with!a!J/V!trace!very!similar!to!that!of!a!simple!
C60!junction,!i.e.!ITO/C60/Al.
19
!!It!is!likely!that!the!10!nm!bDIP!film!is!not!continuous!and!the!
low!voltage!is!due!to!direct!C60/ITO!contacts.!!!
External!quantum!efficiency!(EQE)!plots!are!shown!in!Figure!3d.!!Strong!
photoresponse!from!bDIP!and!C60!are!seen!at!570/780!nm!and!340/450!nm,!respectively.!!
Similar!to!the!trend!seen!in!JSC,!there!was!minimal!enhancement!in!EQE!when!increasing!
the!thickness!from!40!nm!to!70!nm.!!
The!fill!factors!change!proportionally!with!bDIP!thickness!up!to!roughly!50!nm,!
suggesting!that!these!devices!have!improved!charge!conduction!or!induced!favorable!
morphology!with!thicker!bDIP!layers.!!The!conduction!is!facilitated!by!the!π/π!interaction!
between!the!fused!benzene!rings,!which!is!expected!to!enhance!the!carrier/hopping!rate.!!
Despite!being!limited!by!the!bilayer!structure,!the!best!performing!bilayer!device!(70!nm)!
achieved!a!PCE!of!4.5%.!
!
Figure(3.2(J#V(Plot(and(bDIP/C60(Bilayer(Device(Structure.!Representative!J/V!curves!(b)!under!light!
(solid!lines)!and!dark!(dashed!lines)!conditions.!!Some!curves!omitted!for!clarity.!
! 39!
While!the!JSC!increases!with!bDIP!thickness,!it!is!important!to!note!that!the!increase!
in!JSC!is!not!linearly!correlated!to!the!bDIP!thickness.!!A!doubling!of!the!bDIP,!from!35!nm!to!
70!nm,!increases!the!photocurrent!by!less!than!10%.!!Furthermore,!at!thicknesses!greater!
than!70!nm,!JSC!!decreases!with!increasing!bDIP.!!The!drop!in!JSC!upon!increasing!the!bDIP!
layer!beyond!70!nm!is!expected,!since!the!bDIP!that!is!farther!than!the!exciton!diffusion!
length!from!the!D/A!interface!contributes!to!absorption,!but!does!not!generate!a!
photocurrent,!thus!filtering!some!of!the!light!from!reaching!the!“active”!bDIP!near!the!C60!
layer.!!This!phenomenon!has!been!seen!for!other!highly!absorbing!dyes,!such!as!
squaraines.
20
!!While!a!gradual!decrease!in!Jsc!with!donor!thickness!is!expected!for!thick!
!
!
Figure(3.3(Summary(of(PV(Performance(on(Thickness(Dependence(of(bDIP.!!PV!Performance!of!
bilayer!bDIP:C60!devices!with!different!thickness,!(a)!current/densities,!(b)!VOC!and!FF,!(c)!PCE,!and!(d)!
EQE.!!The!error!bars!represent!device/to/device!variations!for!each!parameter!at!the!given!thickness.!!
Some!error!bars!are!too!small!to!be!seen!in!the!plot.!
! 40!
donor!layers,!the!near!insensitivity!to!donor!thickness!between!35!and!70!nm!is!not!
expected.!!We!believe!that!the!insensitivity!of!JSC!to!donor!thickness!is!due!to!the!structure!
of!the!D/A!interface!and!will!discuss!this!further!below.!!
!
3.4(Neutron(Reflectivity(
! The!device!representation!in!Figure!2a,!which!is!typical!for!describing!lamellar!
OPVs,!suggests!that!the!organic!layers!are!uniform!and!that!sharp!interfaces!exist!between!
donor!and!acceptor.!!Recent!studies!have!suggested!that!this!picture!may!not!be!correct!for!
D/A!materials!that!interact!strongly.
21/24
!!We!have!carried!out!neutron!reflectivity!(NR)!
measurements!on!a!bDIP/C 60!bilayer!to!determine!the!structure!at!the!D/A!interface!
directly,!in!a!manner!analogous!to!what!has!been!reported!for!other!organic!bilayer!
systems.
25/28
!!The!sample!was!prepared!via!thermal!vapor!deposition!at!2!Å/s!on!a!silicon!
wafer!with!the!structure:!Si/SiO 2/bDIP!(300!Å)/C 60!(300!Å).!!!Model!film!stacks!were!
!
Figure(3.4(Neutron(Reflectivity(Fitting(and(Modeling(of(Device(Structure.((The!NR!reflectance!(black!
squares),!with!error!bars,!of!the!film!stack:!C60!(300!Å)/bDIP!(300!Å)/SiO 2/Si!is!shown!here!(b).!!Overlaid!
on!the!data!is!the!simulated!reflectance!spectrum!and!its!χ
2
!value!of!the!discrete!bilayer!(blue!trace),!and!
intermixed!three!layer!model!(red!trace).!In!part!(a)!the!three!layer!model!film!stack’s!SLD!Vs.!depth!
profile!is!shown.!!In!this!plot!the!air/C 60!interface!is!taken!as!0.!!!
! 41!
generated!and!the!reflectance!spectra!were!calculated.!The!model!stacks!were!evaluated!by!
analyzing!the!calculated!spectra!with!a!chi/squared!method!for!goodness!of!fit!to!the!
measured!reflectance!spectrum.
29
!!We!started!with!a!bilayer!model,!similar!to!the!cartoon!
in!Figure!2a.!!The!layer!thickness!and!surface!roughness!were!allowed!to!vary!but,!as!seen!
in!Figure!4b!(blue!trace),!we!were!unable!to!converge!on!a!good!fit,!getting!a!minimum!χ
2!
value!of!74.9.!!However,!upon!the!inclusion!of!a!blended!layer!in!a!three/layer!model!to!fit!
the!data!(Figure!4b),!the!calculated!spectrum!converged!well!on!the!measured!reflectance,!
giving!a!χ
2
!value!of!1.75.!!The!film!stack!model!in!Figure!4a!is!tabulated!in!Table!1.!
! The!fitted!model!to!the!neutron!reflectivity!data!suggests!that!there!is!a!substantial!
amount!of!mixing!at!the!interface!between!bDIP!and!C60,!despite!our!attempt!to!deposit!
discrete!layers.!!!The!neat!C60!and!bDIP!layers!have!thicknesses!of!about!240!±!10!Å!and!
330!±!10!Å,!respectively,!and!the!mixed!layer!has!a!thickness!of!130!±!10!Å!and!a!roughness!
of!100!Å.!!The!roughness,!which!is!nearly!on!the!same!order!as!the!thickness!of!the!mixed!
layer,!generates!a!region!of!continuously!changing!scattering!length!density!(SLD),!from!an!
unknown!C60:bDIP!ratio!at!the!interface!to!pure!C60!deeper!in!the!film.!!!This!model!suggests!
that!during!second!deposition,!the!hot!material!dissolves!some!bDIP!into!the!C60!layer!at!
some!preferred!ratio!that!tails!off!as!the!layer!gets!thicker!and!diffusion!of!bDIP!stops.!
!
Layer( SLD((Å
G2
)( Thickness((Å)( Roughness((Å)(
C60! 5.28!x!10
/06
! 240!! 40!
Mixed!Layer! 3.94!x!10
/06
! 130!! 100!
bDIP! 2.11!x!10
/06
! 330!! 30!
SiO2! 4.10!x!10
/06
! 6! 3!
Si! 2.06!x!10
/06
! ∞! 6!
Table(3.1(Neutron(Reflectivity(Outputs.!!Modeled!SLD,!thicknesses,!and!roughness!of!each!component!
layer!for!a!stack!including!a!mixed!C60:bDIP!layer!as!shown!in!Figure!3.4a.!
! 42!
This!result!is!consistent!with!the!lower!VOC!for!10!and!20!nm!bDIP!devices.!!Since!the!
mixed!region!of!C60and!bDIP!is!on!the!order!of!130!Å,!these!devices!are!likely!to!be!largely!if!
not!entirely!composed!of!a!single!intermixed!layer!bDIP!even!though!the!components!were!
separately!deposited.!!Thus,!C60/ITO!contact!is!unavoidable,!as!the!formation!of!a!neat!bDIP!
layer!cannot!be!achieved,!leading!to!lower!VOC!values.!
! The!presence!of!a!130!Å!mixed!layer!also!explains!the!lack!of!a!substantial!increase!
(or!decrease)!in!JSC!as!the!bDIP!is!made!thicker.!!Since!the!thickness!of!the!mixed!interfacial!
layer!does!not!change!with!the!thickness!of!bDIP!layer!underneath!it,!the!underlying!factors!
responsible!for!photocarrier!generation!may!also!remain!unchanged.!!!If!bDIP!has!a!limited!
exciton!diffusion!length!(LD)!and!JSC!is!dominated!by!photons!absorbed!near!and!inside!of!
the!blended!region,!the!observed!small!differences!in!JSC!can!be!attributed!to!a!constant!
baseline!photocurrent!from!the!near!and!intermixed!region!with!minor!contributions!from!
bDIP!beyond!the!mixed!region.!!!
!
3.5(PlanarGMixed(Heterojunction(Photovoltaic(Devices(
In!order!to!understand!the!nature!of!the!intermixed!layer,!OPVs!were!prepared!with!
a!mixed!bDIP/C60!layer!between!neat!bDIP!and!C60!layers,!forming!a!planar/mixed!
heterojunction!(PMHJ)!device.!!In!several!studies,!PMHJ!devices!have!been!shown!to!be!the!
optimal!architecture,!outperforming!their!bulk!heterojunction!(BHJ)!or!planar!
heterojunction!counterparts.
30/33
!!The!addition!of!the!mixed!phase!can!lead!to!an!
enhancement!in!Jsc!via!an!increase!in!the!interfacial!area!between!the!donor!and!
acceptor.
34/36
!!The!first!planar/mixed!heterojunction!device!consists!of!a!thin!layer!of!1!to!1!
bDIP/C 60!blend,!i.e.$ITO/bDIP!35!nm/mixed/bDIP/C60!10!nm/C 60!35!nm/BCP/Al,!as! shown!
! 43!
in!Figure!5c.!!The!total!amount!of!bDIP!deposited!was!the!same!as!that!in!a!40!nm!bDIP!
bilayer!OPV,!used!as!control!for!comparison.!!The!mixed!layer!was!deposited!at!rates!of!
either!4.0!or!0.4!Å/s,!while!the!other!organic!layers!were!deposited!at!2!Å/s,!the!same!rate!
used!for!the!bilayer!control.!!The!PMHJ!devices!prepared!at!a!high!deposition!rate!perform!
poorly!compared!to!the!bilayer!control!(Table!2).!!The!performance!of!the!PMHJ!device!
improved!significantly!when!the!mixed!layer!was!deposited!at!the!slower!rate,!increasing!
Jsc,!Voc,!and!FF,!leading!to!a!PCE!of!2.3%!for!the!0.4!Å/s!device.!!The!EQE,!as!shown!in!Figure!
6b,!reflects!these!enhancements!with!at!least!two/fold!increase!in!photoresponse!across!all!
wavelengths.!
Though!the!total!amount!of!material!in!the!mixed!layers!are!identical,!the!spectral!
response!of!the!devices!prepared!at!high!and!low!depositions!rates!are!not!the!same.!!The!
!
Figure(3.5(J#V(and(EQE(Plots(of(Rate(Dependence(in(bDIP:C60(PMHJ(Devices.((Representative!J/V!
curves!(a)!under!light!(solid!lines)!and!dark!(dashed!lines)!conditions,!EQE!(b),!and!device!structure!(c)!of!
rate/dependent!planar/mixed!heterojunction!devices.!
!
Rate (Å/s) J
sc
(mA/cm
2
) V
oc
(V) FF η (%)
P-M 4.0 Å/s 1.49 0.75 0.20 0.23
P-M 0.4 Å/s 6.32 0.84 0.42 2.25
Bilayer
8.11 0.79 0.51 3.06
Table(3.2(PV(Summary(of(Rate(Dependence(in(bDIP:C60(PMHJ(Devices.((Summary!of!PV!parameters!for!
rate/dependent!PMHJ!devices!and!the!control!bilayer!of!structure:!ITO/bDIP/C 60/BCP/Al .!
(
!
! 44!
relative!C60!and!bDIP!responses!for!the!two!devices!differ.!!In!Figure!5b,!the!device!
prepared!with!a!high!deposition!rate!shows!weaker!C60!response!(400/550!nm)!relative!to!
its!bDIP!response!(550/725!nm)!than!is!seen!for!the!device!prepared!at!a!slow!deposition!
rate.!!It!has!been!shown!that!the!C60!absorption!between!400!and!550!nm!is!due!to!an!
intermolecular!charge/transfer!(CT),!and!depends!strongly!on!the!C60!concentration!in!
mixed!thin!films.
37/38
!!The!C60!CT!absorbance!of!a!mixed!film!decreases!exponentially!with!
the!amount!of!dopant.!!A!film!composed!of!a!homogeneous!1:1!mixture!shows!a!decrease!in!
CT!absorption!of!40%!relative!to!a!neat!thin!film!of!C60.!!The!marked!decrease!in!CT!
absorbance!observed!when!the!mixed!layer!is!deposited!at!4.0!Å/s!suggests!that!the!bDIP/
C60!film!is!intimately!mixed.!!In!contrast,!the!film!prepared!at!the!slower!deposition!rate!
shows!a!clear!peak!at!450!nm,!consistent!with!separate!and!crystalline!domains!of!bDIP!
and!C60!in!the!thin!film.!
Atomic!force!microscopy!(AFM)!was!used!to!investigate!the!effect!of!deposition!rate!
on!the!morphology!of!these!blended!films!shown!in!Figure!7.!!Films!of!the!4.0!and!0.4!Å/s!
intermixed!layer!deposited!on!a!substrate!consisting!of!35!nm!of!bDIP!on!ITO!were!
!
Figure(3.6(AFM(Images(of(1:1(bDIP:C60(Films.!!AFM!images!of!1:1!bDIP:C60!!films!with!different!deposition!
rates:!!4.0!Å/s!(left),!rrms!=!1.43!nm!and!0.4!Å/s!(right),!rrms!=!2.35!nm.!!The!images!are!5.00!µm!by!5.00!µm.!
! 45!
scanned.!The!film!prepared!with!a!4.0!Å/s!rate!gives!a!lower!root!mean!square!roughness,!
rrms!=!1.43!nm,!than!the!one!prepared!at!0.4!Å/s,!with!r rms!=!2.35!nm.!!The!average!domain!
sizes!of!these!two!films!are!drastically!different.!!At!4.0!Å/s,!a!larger!length!for!the!phase!
separated!feature!around!0.4!µm!is!observed!compared!to!~0.1!µm!for!the!0.4Å/s!film.!!A!
rougher!film!with!smaller!domains!suggests!that!more!interfacial!area!is!available!for!
exciton!dissociation,!which!can!improve!device!performance.!!Despite!these!considerable!
improvements,!the!resulting!2.3%!PCE!is!still!below!that!of!the!bilayer!control!device.!
Varying!the!ratio!of!bDIP!and!C60!in!the!mixed!layer!gave!PMHJ!devices!with!a!
similar!PCE!to!the!bilayer!device.!!Three!PMHJ!devices!were!examined,!shown!in!Figure!7,!
with!different!intermixed!layer!bDIP:C60!ratios!(1:1,1:2,!and!1:3)!that!were!deposited!at!a!
constant!rate!of!0.2!Å/s!for!bDIP!and!0.2!Å/s!to!0.6!Å/s!for!the!different!C 60!ratios.!!All!bDIP!
PMHJ!devices!have!VOC!around!0.82!V,!which!is!higher!than!that!of!the!bilayer!control.!!!As!
!
Figure(3.7(J#V(and(EQE(Plots(of(Composition(Dependence(in(bDIP:C 60PMHJ(Devices.(( Representative!J/
V!curves!(a)!under!light!(solid!lines)!and!dark!(dashed!lines)!conditions,!and!EQE!(b)!of!ratio/dependent!
planar/mixed!heterojunction!devices.!
!
Ratio((bDIP:C 60)( JSC((mA/cm
2
)
(
VOC((V)( FF( η (%)(
1:1! 6.32! 0.84! 0.42! 2.25!
1:2! 7.04! 0.82! 0.43! 2.49!
1:3! 8.42! 0.82! 0.55! 3.76!
Bilayer! 8.11! 0.79! 0.51! 3.06!
Table(3.3(PV(Summary(of(Composition(Dependence(in(bDIP:C 60(PMHJ(Devices.!!Summary!of!PV!
parameters!for!ratio/dependent!PMHJ!devices!and!the!control!bilayer!of!structure:!ITO/bDIP/C 60/BCP/Al .!
! 46!
the!mixed!layer!becomes!more!C60!rich,!JSC!and!FF!both!increase,!leading!to!an!overall!
improvement!in!PCE!from!2.3%!for!the!1:1!device!to!3.8%!for!the!1:3!device.!!As!listed!in!
Table!3,!the!1:3!ratio!device!most!closely!represents!the!bilayer!device.!!!The!PMHJ!1:3!
device!generally!outperforms!the!bilayer!analogue.!!Their!respective!values!for!JSC!are!
8.42!mA/cm
2
!versus!8.11!mA/cm2;!a!V OC!of!0.82!V!comparable!to!0.79!V;!and!a!FF!of!0.55!
instead!of!0.51.!
The!EQE!plot!in!Figure!7b,!shows!the!photoresponse!of!bDIP!from!550!nm!to!
780!nm!increasing!with!C60!concentration,!nearly!overlapping!with!the!bilayer!trace!in!this!
region!at!1:3!ratio.!!The!presence!of!a!red!shoulder!around!750!nm!which!is!absent!at!lower!
C60!loading!also!reinforces!the!interfacial!similarity!between!the!1:3!PMHJ!and!bilayer!
device.!!The!main!contribution!to!the!superior!1:3!PMHJ!over!the!bilayer!is!clearly!shown!
from!the!higher!C60!photoresponse!ranging!from!350!nm!to!525!nm.!!The!1:3!PMHJ!has!
~13%!higher!EQE!than!the!bilayer,!which!is!likely!the!origin!of!the!increase!in!JSC.!!These!
effects!result!in!a!25%!improvement!in!PCE!from!the!bilayer!device!when!preparing!an!
intentionally!mixed!PMHJ!of!a!given!thickness,!and!further!confirm!that!even!in!a!bilayer!
device,!the!interface!is!not!discrete.!
(
3.6(Conclusion(
! We!have!demonstrated!the!use!of!a!π/extended!BODIPY!dye!in!OPV!devices!to!
successfully!harvest!red/NIR!photons!out!to!800!nm.!!The!best!device!showed!a!PCE!of!
4.5%!in!a!bilayer!structure.!!The!observed!insensitivity!of!the!bilayer!devices!to!bDIP!
thickness!is!due!to!the!existence!of!an!inherent!mixed!layer!at!the!D/A!interface.!!Though!
each!material!was!deposited!separately!during!fabrication!of!the!lamellar!devices,!
! 47!
spontaneous!mixing!of!C60!and!bDIP!was!unavoidable.!!Neutron!reflectivity!experiment!
estimates!the!thickness!of!the!mixed!layer!between!C60!and!bDIP!to!be!approximately!
13!nm.!!This!layer!acts!as!the!primary!photocurrent!generator!and!significantly!impacts!the!
PCE.!!Its!properties!can!be!controlled!via!deposition!rate!and!blend!ratio.!!PMHJ!devices!
with!a!slower!deposition!rate!in!the!intermixed!layer!results!in!a!higher!PCE!due!to!
different!morphology.!!The!PV!performance!of!devices!with!different!blend!ratios!reveal!
that!the!natively!mixed!region!has!a!bDIP:C60!ratio!close!to!that!of!1:3.!!Contrary!to!what!is!
usually!expected!when!fabricating!a!bilayer!device,!an!unintentional!blended!layer!may!be!
present!in!some!or!all!lamellar!devices.!!The!thickness!will!vary!depending!on!the!
miscibility!of!the!two!components.!!The!PMHJ/like!picture!was!clearly!the!best!
representation!of!bDIP/C60!based!OPVs!and!may!be!the!most!realistic!representation!of!for!
the!majority!of!lamellar!devices.!
(
3.7(Experimental(
Thin!film!absorption!was!taken!from!a!vacuum!deposited!film!of!bDIP!on!quartz.!
UV−VIS!spectra!were!recorded!on!a!Hewlett/Packard!4853!Diode!Array!Spectrometer.!
Cyclic!voltammetry!(CV)!measurements!were!performed!using!an!EG&G!
Potentiostat/Galvanostat!model!283.!!Samples!were!run!in!0.1!M!tetra/n/butyl/ammonium!
hexafluorophosphate!solution!in!dichloromethane!purged!with!nitrogen.!!The!counter,!
reference,!and!working!electrodes!were!platinum,!silver,!and!glassy!carbon,!respectively.!!
Scans!were!performed!at!100!mV/s!and!oxidation/reduction!values!were!calibrated!to!
ferrocene/ferrocenium!internal!references.!
! 48!
Atomic!force!Microscopy!was!taken!on!a!Dimension!Icon!Scanning!Probe!
Microscope!(Bruker)!with!PeakForce!tapping!mode.!!A!Scan!Asyst/Air!Tip!(Bruker)!was!
used!to!scan!the!5!µm!by!5!µm!images.!!Image!processing!and!domain!size!analysis!were!
performed!with!Nanoscope!Analysis!software.!
! Organic!and!aluminum!layers!were!deposited!via!vacuum!thermal!deposition!
chamber!(Angstrom!Engineering)!at!2!Å/s!per!source!under!pressure!of!10
/6
!Torr.!!bDIP,!
C60!(MTR!Limited),!and!bathocuproine!(BCP)!(Aldrich)!were!purified!by!thermal!gradient!
sublimation.!!Device!structure!of!the!cells!are!as!follows:!ITO/X/BCP!(100!Å)/Al!(1000!Å);!
where!X!=!bDIP!(100/1100!Å)/C60!(400!Å)!for!thickness!dependence!films!or!X!=!bDIP!
(350!Å)/1:1/1:3!ratio!bDIP:C60!(100!Å)/C60!(350!Å)!for!PMHJ.!!Fast!and!slow!rate!PMHJ!
devices!were!made!with!a!net!rate!of!4.0!Å/s!with!2.0!Å/s!from!each!bDIP!and!C60!source,!
or!0.4!Å/s!with!0.2!Å/s!source!rates,!respectively.!!Concentration/dependent!devices!
were!fabricated!with!a!constant!rate!of!bDIP!at!0.2!Å/s!and!varying!the!rate!of!C60!from!0.2!
Å/s!to!0.4 Å/s!or!0.6!Å/s!for!1:1,!1:2,!and!1:3!bDIP:C60,!respectively!Indium!tin!oxide!(Thin!
Films,!Inc.)!substrates!were!rinsed!with!Tergitol,!and!boiled!in!each!of!the!organic!solvents,!
tetrachloroethylene,!acetone,!and!alcohol,!for!5!min!each.!!A!10/minute!UV/Ozone!
treatment!prior!loading!into!the!vacuum!chamber!followed.!!After!the!deposition!of!organic!
materials!on!ITO,!a!mask!with!1!mm!diameter!openings!was!placed!on!the!substrate!
followed!by!a!deposition!of!aluminum!(1000!Å)!from!aluminum!shots!(Alfa).!
Current/voltage!characteristics!were!tested!in!dark!and!illumination!under!
simulated!AM!1.5!G!filter!adjusted!to!1!sun!intensity!(100!mW/cm
2
)!with!a!silicon!
photodiode!calibrated!by!the!National!Renewable!Energy!Laboratory.!!Spectral!response!
! 49!
was!measured!using!a!monochromatic!light!source.!!!Spectral!mismatch!and!device!
efficiencies!were!calculated!following!standard!procedure.
40
!!The!PV!parameters!of!all!
devices!reported!were!average!over!at!least!3!devices,!and!at!least!eight!devices!for!those!
ranging!from!20!nm!to!60!nm.!!Statistical!analysis!was!performed!to!obtained!the!average!
values!and!standard!errors!for!the!reported!data.!
Sample!film!stacks!for!neutron!reflectivity!measurements!were!made!by!thermal!
vapor!evaporation!onto!silicon!wafers!with!a!native!oxide!layer!on!their!surface.!!These!
stacks!were!prepared!in!a!nitrogen!atmosphere!and!measured!in!air!at!the!National!
Institute!of!Standards!and!Technology!using!their!NG/7!Horizontal!Neutron!Reflectometer.!!
The!programs!from!the!reflpak!suite!were!used!for!elements!of!the!data!reduction!and!
fitting!film!stack!models!to!the!reflectometry!spectra.
29
! !
! 50!
References(
!
1.! Lin,!Y.;!Li,!Y.;!Zhan,!X.,!Small!molecule!semiconductors!for!high/efficiency!organic!
photovoltaics.!Chem.$Soc.$Rev.$2012,!41!(11),!4245/4272.!
2.! Zhou,!J.;!Zuo,!Y.;!Wan,!X.;!Long,!G.;!Zhang,!Q.;!Ni,!W.;!Liu,!Y.;!Li,!Z.;!He,!G.;!Li,!C.;!Kan,!B.;!
Li,!M.;!Chen,!Y.,!Solution/Processed!and!High/Performance!Organic!Solar!Cells!Using!Small!
Molecules!with!a!Benzodithiophene!Unit.!J.$Am.$Chem.$Soc.$2013,!135!(23),!8484/8487.!
3.! Kyaw,!A.!K.!K.;!Wang,!D.!H.;!Gupta,!V.;!Leong,!W.!L.;!Ke,!L.;!Bazan,!G.!C.;!Heeger,!A.!J.,!
Intensity!Dependence!of!Current–Voltage!Characteristics!and!Recombination!in!High/
Efficiency!Solution/Processed!Small/Molecule!Solar!Cells.!ACS$Nano$2013,!7!(5),!4569/
4577.!
4.! Cnops,!K.;!Rand,!B.!P.;!Cheyns,!D.;!Verreet,!B.;!Empl,!M.!A.;!Heremans,!P.,!8.4%!
efficient!fullerene/free!organic!solar!cells!exploiting!long/range!exciton!energy!transfer.!Nat$
Commun$2014,!5,!1/6.!
5.! Sarma,!T.;!Panda,!P.!K.;!Setsune,!J./i.,!Bis/naphthobipyrrolylmethene!derived!BODIPY!
complex:!an!intense!near/infrared!fluorescent!dye.!Chem.$Commun.$2013,!49,!9806/9808.!
6.! Ulrich,!G.;!Goeb,!S.!b.;!De!Nicola,!A.;!Retailleau,!P.;!Ziessel,!R.,!Chemistry!at!Boron:!
Synthesis!and!Properties!of!Red!to!Near/IR!Fluorescent!Dyes!Based!on!Boron/Substituted!
Diisoindolomethene!Frameworks.!J.$Org.$Chem.$2011,!76!(11),!4489/4505.!
7.! Kowada,!T.;!Yamaguchi,!S.;!Fujinaga,!H.;!Ohe,!K.,!Near/infrared!BODIPY!dyes!
modulated!with!spirofluorene!moieties.!Tetrahedron$2011,!67!(17),!3105/3110.!
8.! Jiao,!C.;!Huang,!K./W.;!Wu,!J.,!Perylene/Fused!BODIPY!Dye!with!Near/IR!
Absorption/Emission!and!High!Photostability.!Org.$Lett.$2011,!13!(4),!632/635.!
9.! Kim,!B.;!Ma,!B.;!Donuru,!V.!R.;!Liu,!H.;!Frechet,!J.!M.!J.,!Bodipy/backboned!polymers!as!
electron!donor!in!bulk!heterojunction!solar!cells.!Chem.$Commun.$2010,!46!(23),!4148/
4150.!
10.! Kubo,!Y.;!Watanabe,!K.;!Nishiyabu,!R.;!Hata,!R.;!Murakami,!A.;!Shoda,!T.;!Ota,!H.,!Near/
Infrared!Absorbing!Boron/dibenzopyrromethenes!that!Serve!As!Light/Harvesting!
Sensitizers!for!Polymeric!Solar!Cells.!Org.$Lett.$2011,!13!(17),!4574/4577.!
11.! Kolemen,!S.;!Bozdemir,!O.!A.;!Cakmak,!Y.;!Barin,!G.;!Erten/Ela,!S.;!Marszalek,!M.;!Yum,!
J./H.;!Zakeeruddin,!S.!M.;!Nazeeruddin,!M.!K.;!Gratzel,!M.;!Akkaya,!E.!U.,!Optimization!of!
distyryl/Bodipy!chromophores!for!efficient!panchromatic!sensitization!in!dye!sensitized!
solar!cells.!Chem.$Sci.$2011,!2!(5),!949/954.!
12.! Rousseau,!T.;!Cravino,!A.;!Ripaud,!E.;!Leriche,!P.;!Rihn,!S.;!De!Nicola,!A.;!Ziessel,!R.;!
Roncali,!J.,!A!tailored!hybrid!BODIPY/oligothiophene!donor!for!molecular!bulk!
heterojunction!solar!cells!with!improved!performances.!Chem.$Commun.$2010,!46!(28),!
5082/5084.!
13.! Poe,!A.!M.;!Della!Pelle,!A.!M.;!Subrahmanyam,!A.!V.;!White,!W.;!Wantz,!G.;!
Thayumanavan,!S.,!Small!molecule!BODIPY!dyes!as!non/fullerene!acceptors!in!bulk!
heterojunction!organic!photovoltaics.!Chem.$Commun.$2014,!50!(22),!2913/2915.!
14.! Bura,!T.;!Leclerc,!N.;!Fall,!S.;!Lévêque,!P.;!Heiser,!T.;!Retailleau,!P.;!Rihn,!S.;!Mirloup,!
A.;!Ziessel,!R.,!High/Performance!Solution/Processed!Solar!Cells!and!Ambipolar!Behavior!in!
Organic!Field/Effect!Transistors!with!Thienyl/BODIPY!Scaffoldings.!J.$Am.$Chem.$Soc.$2012,!
134!(42),!17404/17407.!
15.! Shen,!Z.;!Röhr,!H.;!Rurack,!K.;!Uno,!H.;!Spieles,!M.;!Schulz,!B.;!Reck,!G.;!Ono,!N.,!Boron–
Diindomethene!(BDI)!Dyes!and!Their!Tetrahydrobicyclo!Precursors—en!Route!to!a!New!
! 51!
Class!of!Highly!Emissive!Fluorophores!for!the!Red!Spectral!Range.!Chem.KEur.$J.$2004,!10!
(19),!4853/4871.!
16.! D’Andrade,!B.!W.;!Datta,!S.;!Forrest,!S.!R.;!Djurovich,!P.;!Polikarpov,!E.;!Thompson,!M.!
E.,!Relationship!between!the!ionization!and!oxidation!potentials!of!molecular!organic!
semiconductors.!Org.$Electron.$2005,!6!(1),!11/20.!
17.! Djurovich,!P.!I.;!Mayo,!E.!I.;!Forrest,!S.!R.;!Thompson,!M.!E.,!Measurement!of!the!
lowest!unoccupied!molecular!orbital!energies!of!molecular!organic!semiconductors.!Org.$
Electron.$2009,!10!(3),!515/520.!
18.! Wilke,!A.;!Endres,!J.;!Hormann,!U.;!Niederhausen,!J.;!Schlesinger,!R.;!Frisch,!J.;!
Amsalem,!P.;!Wagner,!J.;!Gruber,!M.;!Opitz,!A.;!Vollmer,!A.;!Brutting,!W.;!Kahn,!A.;!Koch,!N.,!
Correlation!between!interface!energetics!and!open!circuit!voltage!in!organic!photovoltaic!
cells.!Appl.$Phys.$Lett.$2012,!101!(23),!233301/4.!
19.! Taima,!T.;!Chikamatsu,!M.;!Bera,!R.!N.;!Yoshida,!Y.;!Saito,!K.;!Yase,!K.,!Insertion!of!
Thin!Interlayers!under!the!Negative!Electrode!of!C60!Schottky/Type!Photovoltaic!Cells.!J.$
Phys.$Chem.$B$2003,!108!(1),!1/3.!
20.! Wang,!S.;!Mayo,!E.!I.;!Perez,!M.!D.;!Griffe,!L.;!Wei,!G.;!Djurovich,!P.!I.;!Forrest,!S.!R.;!
Thompson,!M.!E.,!High!efficiency!organic!photovoltaic!cells!based!on!a!vapor!deposited!
squaraine!donor.!Appl.$Phys.$Lett.$2009,!94!(23),!233304/3.!
21.! Collins,!B.!A.;!Gann,!E.;!Guignard,!L.;!He,!X.;!McNeill,!C.!R.;!Ade,!H.,!Molecular!
Miscibility!of!Polymer−Fullerene!Blends.!J.$Phys.$Chem.$Lett.$2010,!1!(21),!3160/3166.!
22.! Ma,!W.;!Tumbleston,!J.!R.;!Wang,!M.;!Gann,!E.;!Huang,!F.;!Ade,!H.,!Domain!Purity,!
Miscibility,!and!Molecular!Orientation!at!Donor/Acceptor!Interfaces!in!High!Performance!
Organic!Solar!Cells:!Paths!to!Further!Improvement.!Adv.$Energy$Mater.$2013,!3!(7),!864/
872.!
23.! Treat,!N.!D.;!Brady,!M.!A.;!Smith,!G.;!Toney,!M.!F.;!Kramer,!E.!J.;!Hawker,!C.!J.;!
Chabinyc,!M.!L.,!Interdiffusion!of!PCBM!and!P3HT!Reveals!Miscibility!in!a!Photovoltaically!
Active!Blend.!Adv.$Energy$Mater.$2011,!1!(1),!82/89.!
24.! Treat,!N.!D.;!Varotto,!A.;!Takacs,!C.!J.;!Batara,!N.;!Al/Hashimi,!M.;!Heeney,!M.!J.;!
Heeger,!A.!J.;!Wudl,!F.;!Hawker,!C.!J.;!Chabinyc,!M.!L.,!Polymer/Fullerene!Miscibility:!A!Metric!
for!Screening!New!Materials!for!High/Performance!Organic!Solar!Cells.!J.$Am.$Chem.$Soc.$
2012,!134!(38),!15869/15879.!
25.! Giovanna,!F./C.,!Neutron!reflectivity!at!the!solid/liquid!interface:!examples!of!
applications!in!biophysics.!J.$Phys.:$Condens.$Matter$2001,!13!(21),!4973.!
26.! Ott,!F.,!Neutron!Reflectivity.!In!Surface$Science$Techniques,!Bracco,!G.;!Holst,!B.,!Eds.!
Springer!Berlin!Heidelberg:!2013;!Vol.!51,!pp!307/332.!
27.! Russell,!T.!P.,!X/ray!and!neutron!reflectivity!for!the!investigation!of!polymers.!Mater.$
Sci.$Rep.$1990,!5!(4),!171/271.!
28.! Zhou,!X./L.;!Chen,!S./H.,!Theoretical!foundation!of!X/ray!and!neutron!reflectometry.!
Phys.$Rep.$1995,!257!(4–5),!223/348.!
29.! Kienzle,!P.!A.;!O'Donovan,!K.!V.;!Ankner,!J.!F.;!Berk,!N.!F.;!Majkrzak,!C.!F.!NIST!Center!
for!Neutron!Research!Reflectometry!Software.!http://www.ncnr.nist.gov/reflpak/.!
30.! Xue,!J.;!Rand,!B.!P.;!Uchida,!S.;!Forrest,!S.!R.,!A!Hybrid!Planar–Mixed!Molecular!
Heterojunction!Photovoltaic!Cell.!Adv.$Mater.$2005,!17!(1),!66/71.!
31.! Ojala,!A.;!Burckstummer,!H.;!Hwang,!J.;!Graf,!K.;!von!Vacano,!B.;!Meerholz,!K.;!Erk,!P.;!
Wurthner,!F.,!Planar,!bulk!and!hybrid!merocyanine/C60!heterojunction!devices:!a!case!
! 52!
study!on!thin!film!morphology!and!photovoltaic!performance.!J.$Mater.$Chem.$2012,!22!
(10),!4473/4482.!
32.! Peumans,!P.;!Uchida,!S.;!Forrest,!S.!R.,!Efficient!bulk!heterojunction!photovoltaic!cells!
using!small/molecular/weight!organic!thin!films.!Nature$2003,!425!(6954),!158/162.!
33.! Hiramoto,!M.;!Suemori,!K.;!Yokoyama,!M.,!Photovoltaic!Properties!of!
Ultramicrostructure/Controlled!Organic!Co/Deposited!Films.!Jpn.$J.$Appl.$Phys.$2002,!41!
(4S),!2763.!
34.! Walker,!B.;!Tamayo,!A.!B.;!Dang,!X./D.;!Zalar,!P.;!Seo,!J.!H.;!Garcia,!A.;!Tantiwiwat,!M.;!
Nguyen,!T./Q.,!Nanoscale!Phase!Separation!and!High!Photovoltaic!Efficiency!in!Solution/
Processed,!Small/Molecule!Bulk!Heterojunction!Solar!Cells.!Adv.$Funct.$Mater.$2009,!19!
(19),!3063/3069.!
35.! Schünemann,!C.;!Wynands,!D.;!Wilde,!L.;!Hein,!M.!P.;!Pfützner,!S.;!Elschner,!C.;!
Eichhorn,!K./J.;!Leo,!K.;!Riede,!M.,!Phase!separation!analysis!of!bulk!heterojunctions!in!
small/molecule!organic!solar!cells!using!zinc/phthalocyanine!and!C60.!Phys.$Rev.$B$2012,!85!
(24),!245314.!
36.! Khlyabich,!P.!P.;!Burkhart,!B.;!Rudenko,!A.!E.;!Thompson,!B.!C.,!Optimization!and!
simplification!of!polymer–fullerene!solar!cells!through!polymer!and!active!layer!design.!
Polymer$2013,!54!(20),!5267/5298.!
37.! Bartynski,!A.!N.;!Trinh,!C.;!Panda,!A.;!Bergemann,!K.;!Lassiter,!B.!E.;!Zimmerman,!J.!D.;!
Forrest,!S.!R.;!Thompson,!M.!E.,!A!Fullerene/Based!Organic!Exciton!Blocking!Layer!with!
High!Electron!Conductivity.!Nano$Lett.$2013,!13!(7),!3315/3320.!
38.! Kazaoui,!S.;!Minami,!N.;!Tanabe,!Y.;!Byrne,!H.!J.;!Eilmes,!A.;!Petelenz,!P.,!
Comprehensive!analysis!of!intermolecular!charge/transfer!excited!states!in!C60!and!C70!
films.!Phys.$Rev.$B$1998,!58!(12),!7689/7700.!
39.! Okujima,!T.;!Jin,!G.;!Hashimoto,!Y.;!Yamada,!H.;!Uno,!H.;!Ono,!N.,!Synthesis!of!4,7/
Dihydro/2H/isoindole!Derivatives!via!Diels/Alder!Reaction!of!Tosylacetylene.!Heterocycles$
2006,!70!(1),!619!/!626.!
40.! Shrotriya,!V.;!Li,!G.;!Yao,!Y.;!Moriarty,!T.;!Emery,!K.;!Yang,!Y.,!Accurate!Measurement!
and!Characterization!of!Organic!Solar!Cells.!Adv.$Funct.$Mater.$2006,!16!(15),!2016/2023.!

! !
! 53!
Chapter(4.((
NitrileGFunctionalized(BODIPY(for(C
60
(Sensitization(
4.1(Introduction(
While!the!small/molecule
1
!and!polymeric
2
!materials!have!been!extensively!used!as!
electron!donors!in!OPVs,!material!exploration!for!electron!acceptor
3/4
!is!dwarfed!in!
comparison.!!!One!class!of!acceptor!material!that!is!used!ubiquitously!in!most!high/
performing!devices!is!fullerenes.!!Though!fullerenes!such!as!C60!and!PCBM!exhibit!excellent!
thin/film!absorptivity!and!electron!mobility,!their!constraining!absorption!profile!and!high!
cost!are!barriers!for!commercialization!of!OPVs.
4
!Thus,!it!is!desirable!to!explore!alternative!
electron!acceptors!that!not!only!have!comparable!properties!of!C60,!but!also!chemically!
versatile!to!allow!modification!to!tune!energetics!and!absorption!profile.!
There!are!a!couple!strategies!that!can!be!utilized!towards!designing!a!new!acceptor!
material:!1)!screening!for!a!new!molecular!core,!or!2)!modify!existing!molecules.!!Perylene!
diimide!dyes!are!an!emerging!class!of!molecule!that!has!the!necessary!intrinsic!energetics!
as!well!as!high!electron!affinity!that!shows!a!potential!alternative!to!C60.
5/7
!Alternatively,!
numerous!existing!electron!donors!have!been!modified!to!act!as!polymeric
8/12
!or!small/
molecule
13/19
!acceptors.!!!The!general!scheme!of!modifying!these!molecules!are!to!install!
electron/withdrawing!functional!groups!such!as!nitrile
9/10,!12/13,!18
,!dicyanovinylene
8,!14,!17,!19
,!
or!halides
20/21
!on!the!molecular!cores!of!interest.!!!The!addition!of!these!electron/
withdrawing!groups!pulls!down!the!lowest!unoccupied!molecular!orbital!(LUMO),!enabling!
them!to!be!used!as!an!electron!acceptor.!
! 54!
Boron!dipyrromethenes!(BODIPY)!is!a!class!of!highly!versatile!and!absorbing!dye!
that!has!been!extensively!studied
22/23
!and!proved!to!be!a!good!material!for!solar!cell!
application!as!donors
24/28
,!sensitizer
29/31
,!and!acceptor.
32/33
!!Previously,!we!have!used!
BODIPY!as!an!electron!donor!in!OPVs!and!obtained!excellent!result.
25
!!Nitrile/BODIPY!
derivatives,!such!as!cDIP,!have!been!used!for!laser
34
,!sensors
35/36
,!and!fluorescent!tags.
37
!!!It!
possesses!suitable!energetics!as!electron!acceptor!and!its!performance!has!not!been!
investigated!in!OPV.!!In!this!chapter,!we!focus!on!employing!cDIP!as!an!electron!acceptor!
and!C60!sensitizer!with!copper!phthalocyanine!(CuPc)!in!lamellar!photovoltaic!devices.!
!
4.2(Synthesis(of(cDIP(
Following!literature!procedure
37
,!the!addition!of!nitrile!groups!to!a!BODIPY!core!
was!achieved!via!nitrile/substituted!pyrrole!to!the!BODIPY!acceptor,!cDIP,!in!moderate!
yields.!!In!the!first!two!steps,!both!the!acidic!deprotection!of!the!amine!group!to!the!HBr!
salt!and!subsequent!addition!of!the!amino/nitrile!proceeded!in!excellent!yields.!!Facile!
!
Figure(4.1(Structure(and(Absorption(Profiles(of(CuPc(and(C60.!!Overlay!of!absorption!profiles!of!
solar!flux!with!C60!and!CuPc,!common!materials!for!OPV.!!
! 55!
purification!of!the!two!intermediates!was!completed!through!filtration!and!
recrystallization.!!!A!marked!drop!in!reaction!yield!was!observed!for!the!following!Grignard!
reaction!with!methyl!magnesium!bromide.!!The!reaction!mixture!was!difficult!to!purify!and!
losses!during!extraction!were!unavoidable.!!The!resulting!oil!mixture!was!recrystallized!
over!several!days!in!diethyl!ether!and!used!in!the!next!step!without!further!purification.!!
The!final!ring/closing!pyrrole!synthesis!proceeded!without!much!trouble!in!high!yields.!!
The!cyano/pyrrole!was!purified!via!column!chromatography!in!1:1!dichloromethane!and!
hexane!followed!by!recrystallization!in!the!same!solvents.!!The!white!pyrrole!crystals!were!
reacted!with!standard!BODIPY!reagents!over!two!steps!to!form!the!desired!
dipyrromethenes!compound,!cDIP.!!While!the!product!yield!is!not!high,!it!does!fall!into!
typical!BODIPY!reaction!yields!ranging!from!30!–!50%.
22
!
!
!
Scheme(4.1((Synthesis(of(cDIP(
! 56!
4.3(Material(Properties(of(cDIP(
!Typical!of!BODIPY!dyes,!cDIP!exhibits!high!molar!absorptivity!with!ε(=!1.46!x!10
5!
M
/
1
cm
/1
!at!absorption!maximum!of!499!nm!and!relatively!high!photolouminescence!quantum!
yield!of!Φ!=!0.69.!!In!Figure!2,!solid/state!absorption!is!red/shifted!by!23!nm!and!broadened!
significantly!by!40!nm!(FWHMsol!=!32!nm;!FWHMfilm!=!72!nm).!!Unlike!the!small!Stoke’s!
shift!of!21!nm!observed!in!solution,!the!solid/state!emission!has!a!marked!Stoke’s!shift!of!
about!70!nm!with!the!broadened!emission!maxima!at!592!and!618!nm.!!The!deviation!of!
solid/state!from!solution!properties!can!be!attributed!to!molecular!aggregation.!!The!planar!
BODIPY!core!allows!the!tightly!packed!molecules!to!increase!π/orbital!interactions,!thus!
broadening!and!red/shifting!the!absorption!and!emission.!
The!molecular!structures,!highest!occupied!molecular!orbital!(HOMO),!and!lowest!
unoccupied!molecular!orbital!(LUMO)!energies!are!presented!in!Fig.!3.!!The!values!for!
CuPc
38
!and!C60
39
!were!obtained!from!literature,!while!cDIP!was!calculated!from!cyclic!
voltammetry!data.!!The!incorporation!of!cyano!groups!lowers!the!oxidation!and!reduction!
potential!of!the!cDIP,!lead!to!a!LUMO!of!3.63!eV,!comparable!to!C60’s!3.95!eV.!!As!shown!in!
!
(
Figure(4.2(Absorption(&(Emission(Plots(and(Cyclic(Voltammogram(of(cDIP.!!(a)!Absorption!and!
emission!spectra!of!cDIP!as!thin!film!and!in!dichloromethane.!!(b)!Cyclic!voltammogram!of!cDIP!as!
internal!standard.!
! 57!
Fig.!3.,!this!allows!cDIP!to!be!energetically!compatible!with!donors!that!are!previously!used!
with!C60.!
To!ensure!energy!transfer!occurs!from!cDIP!to!C60,!photoluminescence!quenching!of!
cDIP:C60!blends!and!cDIP!films!were!measured!as!shown!in!Figure!4b.!!The!cDIP!absorption!
in!each!blending!ratio,!centered!on!500!nm,!can!be!observed!Fig.!4a.!with!decreasing!
intensity!as!C60!content!increases.!!As!a!neat!film,!cDIP!shows!strong!emission!starting!at!
520!nm!upon!excitation!at!500!nm.!!In!all!cDIP:C60!blended!films,!however,!the!cDIP!
emission!is!completely!quenched!with!the!same!excitation,!indicating!that!there!is!efficient!
energy!transfer!from!cDIP!to!C60.!!Based!on!these!results,!we!are!confident!that!cDIP!can!be!
used!as!a!sensitizer!for!C60.!
(
4.4(cDIP(as(Electron(Acceptor((
We!were!not!able!obtain!a!working!device!when!cDIP!was!used!as!the!only!electron!
acceptor!with!the!structure!ITO/CuPc!(40!nm)/cDIP!(40!nm)/BCP!(10!nm)/Al!(100!nm),!
BCP!=!bathocuproine.!!Even!though!the!similarities!in!LUMO!energies!suggests!that!energy!
! ! ! !
!
Figure(4.3(Molecular(Structure(and(HOMO(&(LUMO(Energies(for(CuPc,(C60,(and(cDIP.!!Molecular!
structures!and!HOMO/LUMO!energies!of!materials!studied.!!!!
a
Values!were!obtained!via!cyclic!
voltammetry.!!
b
Literature!values!are!used,!ref.!5!and!ref.!6.!
! 58!
transfer!and!charge!separation!should!occur!between!CuPc!and!cDIP,!we!attributed!the!
failure!of!the!devices!to!the!polycrystallinity!of!the!cDIP,!creating!excessive!grain/boundary!
that!act!as!charge!traps!in!the!device.!!Our!speculation!was!confirmed!in!the!AFM!image!in!
Fig.!5.,!showing!large!crystallites!that!are!about!a!microns!in!length.!!It!was!also!observed!
that!neat!cDIP!films!readily!form!crystallites!following!vacuum!deposition!with!features!
observable!with!the!naked!eye.!!In!order!to!overcome!cDIP’s!natural!tendency!to!aggregate,!
we!increase!the!deposition!rate!from!2!Å/s!to!20!Å/s!to!lock!down!the!molecules!before!it!
has!time!to!reorganize!and!reduce!the!grain!size.!!Successful!results!had!been!previously!
demonstrated!with!tetracene!to!control!the!morphology!of!the!film!with!higher!deposition!
rate.
40
!However,!our!attempt!to!minimize!aggregation!with!this!method!also!did!not!result!
in!any!improvement!for!cDIP!devices.!!
(
4.5(cDIP(as(C60(Sensitizer(!
!! Since!the!LUMOs!of!cDIP!and!C60!are!similar,!we!postulated!that!a!codeposited!film!
of!the!two!materials!would!be!viable!without!creating!energetic!traps!in!the!device!while!
!
Figure(4.4(Thin(Film(Absorptions(of(cDIP(blends(and(PL(Quenching(of(cDIP.!(a)!Thin!film!
absorption!and!(b)!emission!of!neat!cDIP!and!cDIP:C60!blends.!!C60!and!cDIP!absorptions!increase!and!
decrease,!respectively,!with!higher!C60!content.!!Strong!solid/state!emission!is!observed!for!neat!cDIP,!
while!complete!quenching!is!observed!for!C60:cDIP!blends.!
! 59!
significantly!alleviating!the!aggregation!problem!of!cDIP.!!!Furthermore,!by!utilizing!both!
materials,!there!should!also!be!an!increase!in!photocurrent!from!the!added!spectral!
coverage!of!C60.!!Devices!with!structure!of!ITO/CuPc!(40!nm)/X:1!C60:cDIP!(40!nm)/BCP!
(10!nm)/Al!(100!nm);!(X!=!1,!2,!3)!were!fabricated!and!the!results!are!summarized!in!Fig.!5!
and!Table!1.!!The!sensitized!device!power!conversion!efficiencies!(PCE)!are!all!higher!than!
the!C60!control!at!1.09%.!!The!short/circuit!current!(JSC)!increases!with!decreasing!cDIP!
content!from!4.43!mA/cm
2
,!4.75!mA/cm
2
,!to!4.89!mA/cm
2
!for!1:1,!2:1,!and!3:1!C60:cDIP,!
respectively.!!The!best!performing!device!with!PCE!of!1.42%!is!obtained!from!a!optimal!
blending!ratio!of!3:1!C60:cDIP!with!the!sensitized!JSC!23%!higher!than!the!unsensitized!
device!owing!to!cDIP!absorption.!
The!origin!can!be!clearly!traced!in!the!external!quantum!efficiency!(EQE)!plot,!Fig.!
6b.!!The!EQE!plot!shows!intense!photoresponse!centered!at!500!nm!and!350!nm!from!cDIP,!
which!corresponds!to!the!absorption!peaks!of!cDIP.!!A!higher!concentration!of!cDIP!leads!to!
a!higher!photoresponse!at!500!nm!from!26%!at!3:1!C60:cDIP!to!38%!at!1:1!C60:cDIP.!!!
However,!the!dilution!of!C60!from!cDIP!in!sensitized!devices!results!in!a!50%!reduction!of!
!
Figure(4.5(J#V(Plot(of(CuPc/cDIP(Devices(and(AFM(Image(of(cDIP(Film.!!J/V!plot!of!CuPc/cDIP!devices!of!
varying!thickness!(left).!!None!of!the!devices!exhibit!photodiodic!behavior.!!!AFM!image!(right)!of!a!cDIP!film!
on!glass!substrate!shows!large!crystal!formations.!!
!
! 60!
C60!photocurrent!compared!to!the!C60–only!control!device.!!!!This!loss!is!due!to!the!
concentration!dependence!of!C60!charge/transfer!(CT)!absorption!around!450!nm.!!The!EQE!
response!is!slowly!recovered!as!the!cDIP!sensitizer!is!removed!from!the!blended!film.!!The!
combined!effects!can!be!observed!in!the!PCE!trend!of!the!devices.!!Devices!with!higher!cDIP!
content!perform!poorer!compare!to!the!C60/rich!counterpart,!provided!there!is!some!cDIP!
in!the!film.!!As!the!cDIP!peak!grows,!the!C60!peak!drops!resulting!in!a!trade/off!between!
cDIP!and!C60.!!In!addition,!a!marked!reduction!in!CuPc!photoresponse!between!580!and!
800!nm!is!observed!with!the!losses!of!up!to!33%!in!1:1!C60:cDIP.!!The!presence!of!more!
cDIP!at!the!D/A!interface!can!be!a!source!leading!to!recombination!losses!as!seen!in!the!
!
Figure(4.6(J#V(and(EQE(Plots(of(cDIP GSensitized(Devices.!!Representative!I/V!(a)!and!EQE!(b)!plots!
of!CuPc/C60:cDIP!devices!with!different!C60:cDIP!ratios.!
!
Blend(Ratio( JSC(((mA/cm
2
)
a
( VOC(( (V)( FF( PCE((%)
b
(
C
60
# 3.97#(3.69)# 0.51# 0.58# 1.18#(1.09)#
1:1#C
60
#cDIP# 4.43#(4.20)# 0.49# 0.60# 1.31#(1.14)#
2:1#C
60
#cDIP# 4.75#(4.31)# 0.48# 0.60# 1.36#(1.15)#
3:1#C
60
#cDIP# 4.89#(4.36)# 0.49# 0.58# 1.42#(1.19)#
!
Table(4.1(PV(Summary(of(cDIP GSensitized(Devices.!Photovoltaic!parameters!of!CuPc!/C60:cDIP!
devices!with!different!C60:cDIP!ratios.!!
a
Integrated!current/density!values!from!EQE!and!
b
average!PCE!
in!parenthesis.!!
! 61!
slightly!lower!open/circuit!voltage!(VOC)!from!the!sensitized!devices.!!
Despite!the!losses!the!in!photocurrent,!the!relative!similarities!in!fill/factor!(FF)!
between!the!control!and!sensitized!device!suggest!that!the!incorporation!of!cDIP!molecules!
in!C60!has!largely!no!effect!on!the!film!morphology.!!AFM!images!(Fig.!7.)!of!each!of!the!
different!blend!ratios!shows!the!absence!of!large!cDIP!crystals!and!excessive!grain!
boundaries!that!plague!the!use!of!cDIP!as!neat!acceptor.!The!film!roughness!varies!slightly!
across!blend!ratios,!but!their!uniform!surfaces!do!not!have!substantial!differences!in!
morphological!features.!
While!slightly!lower,!the!nearly!constant!in!VOC!between!the!control!and!sensitized!
!
!
Figure(4.7(AFM(Images(of(cDIP:C60(Films.!AFM!images!of!C60!(a),!1:1!C60:cDIP!(b),!2:1!C60:cDIP!
(c),!3:1!C60:cDIP!(d)!films!on!glass.!!!The!rrms!are!2.2!nm,!9.6!nm,!11.5!nm,!and!25.1!nm,!
respectively!
!
! 62!
devices!suggests!that!cDIP!is!likely!not!involved!in!charge!separation!between!C60!and!CuPc.!!
This!is!further!corroborated!by!devices!containing!only!C60/cDIP,!presented!in!Figure!8.!!
While!energy!transfer!between!cDIP!and!C60!appears!to!be!effective!in!sensitized!devices,!
the!low!photocurrent!here!suggests!that!charge!separation!does!not!happen!efficiently!
between!cDIP!and!C60.!Though!cDIP!is!an!excellent!complementary!absorber,!only!a!small!
amount!of!cDIP!can!be!incorporated!on!this!particular!device!architecture!due!to!the!losses!
of!the!other!two!components.!!
Though!C60!CT!absorption!!can!be!improved!with!higher!C60!loading,!the!recovered!
C60!and!CuPc!contribution!was!insufficient!compared!to!the!control!device.!!!A!discrete!
C60/CuPc!interface!to!preserve!the!CuPc!response!as!well!as!a!neat!C60!layer!to!fully!
recapture!the!CT!absorption!region!around!450!nm.!!The!thin!film!C60!CT!absorption!has!
been!shown!to!recover!once!a!higher!C60!content!is!achieved.
41
!A!20!nm!layer!of!C60!was!
!
!
Figure(4.8(J#V(and(EQE(Plots(of(cDIP/C 60(Devices.!Representative!I/V!and!EQE!plots!C60:cDIP/only!
device!(a),!(b).!
!
(
JSC(((mA/cm
2
)( VOC(( (V)( FF( PCE((%)(
cDIP:C60(1:1! 0.20! 0.43! 0.47! 0.042!
Table(4.2(PV(Summary(of(cDIP/C 60(Devices.!!Photovoltaic!parameters!of!C60:cDIP/only!devices.!
! 63!
inserted!into!the!device!stack!with!the!structure:!ITO/CuPc!(40!nm)/C 60!(20!nm)/X:1!
C60:cDIP!(20!nm)/BCP!(10!nm)/Al!(100!nm);!X!=!1,!2,!3.!!In!Figure!9.!and!Table!3.,!our!
results!reveal!that!the!insertion!of!a!C60!layer!improves!the!device!performance,!with!the!
highest!PCE!of!1.46%!for!an!optimal!C60:cDIP!blend!of!1:1.!!For!all!ratios!of!C60:cDIP!blends,!
the!C60!and!CuPc!photoresponses!at!450!nm!and!650!nm!appear!to!be!identical!as!the!
control!C60/only!device.!!Our!results!show!that!with!a!neat!C60!layer,!we!are!able!to!correct!
for!the!losses!of!CuPc!as!well!as!fully!recover!the!C60!CT!contributions!from!interfacial!and!
dilution!influences.!
There!is!little!variation!in!FF!and!VOC!for!these!devices!with!respect!to!the!control!
!
!
Figure(4.9(J#V(and(EQE(Plots(of(cDIP GSensitized(Devices(with(C 60(Interfacial(Layer.!!Representative!I/V!(a)!
and!EQE!(b)!plots!of!CuPc/C 60/C 60:cDIP!devices!with!different!C60:cDIP!ratios.!
!
Blend(Ratio( JSC(((mA/cm
2
)
*
( VOC(((V)( FF( PCE((%)(
C
60
# 3.97#(3.69)# 0.51# 0.58# 1.18#(1.09)#
1:1#C
60
#cDIP#
4.84#(4.87)# 0.53# 0.57# 1.46#(1.30)#
2:1#C
60
#cDIP#
4.61#(4.79)# 0.52# 0.60# 1.44#(1.26)#
3:1#C
60
#cDIP#
4.44#(4.49)# 0.52# 0.59# 1.34#(1.22)#
Table(4.3(PV(Summary(of(cDIP GSensitized(Devices(with(C 60(Interfacial(Layer.!Photovoltaic!parameters!of!
CuPc!/C 60/C 60:cDIP!devices!with!different!C60:cDIP!ratios.!*Integrated!current/density!values!from!EQE!plot!in!
parenthesis.!
!
! 64!
device.!!For!the!interlayer!device!structure,!a!reverse!trend!for!PCE!and!JSC!is!observed!with!
the!highest!values!obtained!for!the!most!cDIP/rich!device.!!Since!the!C60!interlayer!is!
absorbing!the!majority!of!photons!between!400!and!500!nm,!we!are!able!to!use!a!higher!
cDIP!concentration!for!the!sensitized!layer!without!worrying!about!losses!for!both!C60!and!
CuPc.!!However,!the!EQE!for!cDIP!is!about!50%!lower!than!devices!without!C60!intelayer!
because!the!amount!of!cDIP!in!the!device!is!also!50%!less!due!to!a!thinner!sensitized!layer.!!
Although!the!loss!from!CuPc!response!is!nominal,!the!need!to!balance!C60!and!cDIP!
concentration!still!exists!in!these!devices,!resulting!similar!JSC!and!PCEs!for!both!optimized!
device!structures.!!These!results!demonstrate!that!cDIP!can!act!as!an!effective!sensitizer!
without!interfering!significantly!with!other!processes!in!a!CuPc/C60!device.!
!
4.6(Conclusion(
( While!cDIP!is!a!strong!absorber,!we!demonstrated!that!its!crystallinity!limits!its!use!
as!an!electron!acceptor!in!OPV.!!However,!when!blended!with!C60,!uniform!film!morphology!
can!be!obtained!resulting!in!functional!devices.!!The!addition!of!cDIP!leads!additional!
photons!collected!in!the!visible!region,!but!reduces!the!C60!CT!absorption!due!dilution!
effects.!!Its!presence!also!does!not!affect!the!VOC!and!FF,!indicating!that!it!likely!does!not!
participate!in!charge!separation!between!C60!and!CuPc.!!The!insertion!of!a!neat!C60!layer!
prevents!not!only!the!CT!absorptions!losses,!but!also!recovers!the!majority!of!the!CuPc!
losses!observed!previously.!!The!best!device!with!1.46%!was!achieved!with!a!C60:cDIP!ratio!
of!1:1,!an!23%!increase!compared!to!the!control!device.!!The!use!of!BODIPY!dyes!in!our!
devices!establishes!them!as!versatile!molecules!whose!high!absorptivity!and!lead!to!high/
performing!OPVs.!with!further!studies.!
! 65!
4.7(Experimental(
Unless!noted!otherwise,!all!chemicals!were!purchased!from!Sigma/Aldrich!and!used!
without!further!purification.!!Dry!solvents!were!purified!using!a!Glass!Contour!Solvent!
System!and!all!reactions!were!performed!under!inert!nitrogen!atmosphere.!!!cDIP
35,!37
!was!
synthesized!following!literature!procedure.!!
Thin!film!absorption,!emission,!and!AFM!were!taken!from!vacuum!deposited!films!
on!glass.!!UV−vis!spectra!were!recorded!on!a!Hewlett/Packard!4853!Diode!Array!
Spectrometer.!!Photoluminescence!measurements!were!recorded!on!a!Photon!Technology!
International!QuantaMaster!Model!C/60SE!spectrofluorimeter.!!Atomic!force!microscopy!
was!performed!using!an!Agilent!SPM!5400!in!tapping!mode.!!Cyclic!voltammetry!
measurements!were!performed!using!an!EG&G!Potentiostat/Galvanostat!model!283.!!
Samples!were!run!in!0.1!M!tetra/n/butyl/ammonium!hexafluorophosphate!solution!in!
dichloromethane!purged!with!nitrogen.!!The!counter,!reference,!and!working!electrodes!
were!platinum,!silver,!and!glassy!carbon,!respectively.!!Scans!were!performed!at!100!mV/s!
and!oxidation/reduction!values!were!calibrated!to!ferrocene/ferrocenium!internal!
references.!!LUMO!and!HOMO!values!were!calculated!from!reported!procedures.
42/43
!
! Organic!and!aluminum!layers!were!deposited!via!vacuum!thermal!deposition!
chamber!(Angstrom!Engineering)!under!pressure!of!10
/6
!Torr.!!CuPc,!cDIP,!C60!(MTR!
Limited),!and!bathocuprine!(BCP)!were!purified!by!thermal!gradient!sublimation.!!Device!
structure!of!the!cells!are!as!follows:!ITO/CuPc!(400!Å)/X/BCP!(100!Å)/Al!(1000!Å);!where!
X!=!cDIP!(400Å)!at!2!or!20!Å/s!for!rate!dependence!studies;!X!=!1:1,!2:1,!3:1!C60:cDIP!(400!
Å)!with!C60!at!1!Å/s!and!cDIP!at!1,!0.5,!0.33!Å/s!for!blend!ratio!studies;!X=!C60!(200!Å)/1:1,!
2:1,!or!3:1!C60:cDIP!(200!!Å)!for!C60!interlayer!blended!devices;!X!=!C60!(400!Å)!at!2!Å/s!as!
! 66!
the!control.!Patterned!indium!tin!oxide!(Thin!Films,!Inc.)!substrates!were!rinsed!with!
Tergitol,!and!boiled!in!each!of!the!organic!solvents,!tetrachloroethylene,!acetone,!and!
alcohol,!for!5!min.!!A!10/minute!UV/Ozone!treatment!prior!loading!into!the!vacuum!
chamber!followed.!!After!the!deposition!of!organic!materials!on!ITO,!a!masked!deposition!of!
aluminum!(1000!Å)!from!aluminum!shots!(Alfa)!followed.!!Thermal!treatment!was!done!on!
a!preheated!Wenesco!hotplate!at!100!°C!for!5!minutes.!!Current/voltage!characteristics!
were!tested!in!dark!and!illumination!under!simulated!AM!1.5!G!filter!adjusted!to!1/sun!
intensity!(100!mW/cm
2
)!with!a!silicon!photodiode!calibrated!by!the!National!Renewable!
Energy!Laboratory.!!Spectral!response!was!measured!using!a!monochromatic!light!source.!!!
Spectral!mismatch!and!device!efficiencies!were!calculated!following!standard!procedure
44
.!!
With!the!exception!of!C60/cDIP/devices,!all!reported!device!parameters!are!averaged!from!a!
minimum!of!12!devices.!
! 67!
4.8(NMR(Spectra!
!
!
!
!
! 68!
!
!
!
! 69!
References(
(
(1)! Lin,!Y.;!Li,!Y.;!Zhan,!X.!Small!molecule!semiconductors!for!high/efficiency!organic!
photovoltaics.!Chem.$Soc.$Rev.$2012,!41,!4245/4272.!
(2)! Facchetti,!A.!Polymer!donor–polymer!acceptor!(all/polymer)!solar!cells.!Materials$
Today$2013,!16,!123/132.!
(3)! Kim,!Y.;!Lim,!E.!Development!of!Polymer!Acceptors!for!Organic!Photovoltaic!Cells.!
Polymers$2014,!6,!382.!
(4)! Lin,!Y.;!Zhan,!X.!Non/fullerene!acceptors!for!organic!photovoltaics:!an!emerging!
horizon.!Materials$Horizons$2014,!1,!470/488.!
(5)! Dutton,!G.!J.;!Robey,!S.!W.!Non/fullerene!acceptors:!exciton!dissociation!with!PTCDA!
versus!C60.!Phys.$Chem.$Chem.$Phys.$2015,!17,!15953/15962.!
(6)! Zhao,!D.;!Wu,!Q.;!Cai,!Z.;!Zheng,!T.;!Chen,!W.;!Lu,!J.;!Yu,!L.!Electron!Acceptors!Based!on!
α/Substituted!Perylene!Diimide!(PDI)!for!Organic!Solar!Cells.!Chem.$Mater.$2016,!28,!
1139/1146.!
(7)! Erwin,!P.;!Thompson,!M.!E.!Elucidating!the!interplay!between!dark!current!coupling!
and!open!circuit!voltage!in!organic!photovoltaics.!Appl.$Phys.$Lett.$2011,!98,!/.!
(8)! Zhao,!W.;!Qian,!D.;!Zhang,!S.;!Li,!S.;!Inganäs,!O.;!Gao,!F.;!Hou,!J.!Fullerene/Free!
Polymer!Solar!Cells!with!over!11%!Efficiency!and!Excellent!Thermal!Stability.!Adv.$
Mater.$2016,!28,!4734/4739.!
(9)! Chochos,!C.!L.;!Economopoulos,!S.!P.;!Deimede,!V.;!Gregoriou,!V.!G.;!Lloyd,!M.!T.;!
Malliaras,!G.!G.;!Kallitsis,!J.!K.!Synthesis!of!a!Soluble!n/Type!Cyano!Substituted!
Polythiophene!Derivative: !A!Potential!Electron!Acceptor!in!Polymeric!Solar!Cells.!
The$Journal$of$Physical$Chemistry$C$2007,!111,!10732/10740.!
(10)! Halls,!J.!J.!M.;!Walsh,!C.!A.;!Greenham,!N.!C.;!Marseglia,!E.!A.;!Friend,!R.!H.;!Moratti,!S.!
C.;!Holmes,!A.!B.!Efficient!photodiodes!from!interpenetrating!polymer!networks.!
Nature$1995,!376,!498/500.!
(11)! Vijayakumar,!C.;!Saeki,!A.;!Seki,!S.!Optoelectronic!Properties!of!Dicyanofluorene/
Based!n/Type!Polymers.!Chemistry$–$An$Asian$Journal$2012,!7,!1845/1852.!
(12)! Yu,!G.;!Heeger,!A.!J.!Charge!separation!and!photovoltaic!conversion!in!polymer!
composites!with!internal!donor/acceptor!heterojunctions.!J.$Appl.$Phys.$1995,!78,!
4510/4515.!
(13)! Lim,!Y./F.;!Shu,!Y.;!Parkin,!S.!R.;!Anthony,!J.!E.;!Malliaras,!G.!G.!Soluble!n/type!
pentacene!derivatives!as!novel!acceptors!for!organic!solar!cells.!J.$Mater.$Chem.$
2009,!19,!3049/3056.!
(14)! Schwenn,!P.!E.;!Gui,!K.;!Nardes,!A.!M.;!Krueger,!K.!B.;!Lee,!K.!H.;!Mutkins,!K.;!
Rubinstein/Dunlop,!H.;!Shaw,!P.!E.;!Kopidakis,!N.;!Burn,!P.!L.;!Meredith,!P.!A!Small!
Molecule!Non/fullerene!Electron!Acceptor!for!Organic!Solar!Cells.!Adv.$Energy$Mater.$
2011,!1,!73/81.!
(15)! Shu,!Y.;!Lim,!Y./F.;!Li,!Z.;!Purushothaman,!B.;!Hallani,!R.;!Kim,!J.!E.;!Parkin,!S.!R.;!
Malliaras,!G.!G.;!Anthony,!J.!E.!A!survey!of!electron/deficient!pentacenes!as!acceptors!
in!polymer!bulk!heterojunction!solar!cells.!Chem.$Sci.$2011,!2,!363/368.!
(16)! Woo,!C.!H.;!Holcombe,!T.!W.;!Unruh,!D.!A.;!Sellinger,!A.;!Fréchet,!J.!M.!J.!Phenyl!vs!
Alkyl!Polythiophene:!A!Solar!Cell!Comparison!Using!a!Vinazene!Derivative!as!
Acceptor.!Chem.$Mater.$2010,!22,!1673/1679.!
! 70!
(17)! Zhou,!T.;!Jia,!T.;!Kang,!B.;!Li,!F.;!Fahlman,!M.;!Wang,!Y.!Nitrile/Substituted!QA!
Derivatives:!New!Acceptor!Materials!for!Solution/Processable!Organic!Bulk!
Heterojunction!Solar!Cells.!Adv.$Energy$Mater.$2011,!1,!431/439.!
(18)! Zhou,!Y.;!Ding,!L.;!Shi,!K.;!Dai,!Y./Z.;!Ai,!N.;!Wang,!J.;!Pei,!J.!A!Non/Fullerene!Small!
Molecule!as!Efficient!Electron!Acceptor!in!Organic!Bulk!Heterojunction!Solar!Cells.!
Adv.$Mater.$2012,!24,!957/961.!
(19)! Lin,!Y.;!Zhao,!F.;!He,!Q.;!Huo,!L.;!Wu,!Y.;!Parker,!T.!C.;!Ma,!W.;!Sun,!Y.;!Wang,!C.;!Zhu,!D.;!
Heeger,!A.!J.;!Marder,!S.!R.;!Zhan,!X.!High/Performance!Electron!Acceptor!with!
Thienyl!Side!Chains!for!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2016,!138,!4955/
4961.!
(20)! Bartynski,!A.!N.;!Gruber,!M.;!Das,!S.;!Rangan,!S.;!Mollinger,!S.;!Trinh,!C.;!Bradforth,!S.!
E.;!Vandewal,!K.;!Salleo,!A.;!Bartynski,!R.!A.;!Bruetting,!W.;!Thompson,!M.!E.!
Symmetry/Breaking!Charge!Transfer!in!a!Zinc!Chlorodipyrrin!Acceptor!for!High!
Open!Circuit!Voltage!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2015,!137,!5397/5405.!
(21)! Trinh,!C.;!Kirlikovali,!K.!O.;!Bartynski,!A.!N.;!Tassone,!C.!J.;!Toney,!M.!F.;!Burkhard,!G.!
F.;!McGehee,!M.!D.;!Djurovich,!P.!I.;!Thompson,!M.!E.!Efficient!Energy!Sensitization!of!
C60!and!Application!to!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2013,!135,!11920/
11928.!
(22)! Loudet,!A.;!Burgess,!K.!BODIPY!Dyes!and!Their!Derivatives: !Syntheses!and!
Spectroscopic!Properties.!Chem.$Rev.$2007,!107,!4891/4932.!
(23)! Ulrich,!G.;!Ziessel,!R.;!Harriman,!A.!The!Chemistry!of!Fluorescent!Bodipy!Dyes:!
Versatility!Unsurpassed.!Angew.$Chem.,$Int.$Ed.$2008,!47,!1184/1201.!
(24)! Bura,!T.;!Leclerc,!N.;!Fall,!S.;!Lévêque,!P.;!Heiser,!T.;!Retailleau,!P.;!Rihn,!S.;!Mirloup,!
A.;!Ziessel,!R.!High/Performance!Solution/Processed!Solar!Cells!and!Ambipolar!
Behavior!in!Organic!Field/Effect!Transistors!with!Thienyl/BODIPY!Scaffoldings.!J.$
Am.$Chem.$Soc.$2012,!134,!17404/17407.!
(25)! Chen,!J.!J.;!Conron,!S.!M.;!Erwin,!P.;!Dimitriou,!M.;!McAlahney,!K.;!Thompson,!M.!E.!
High/Efficiency!BODIPY/Based!Organic!Photovoltaics.!ACS$Appl.$Mater.$Interfaces$
2015,!7,!662/669.!
(26)! Kim,!B.;!Ma,!B.;!Donuru,!V.!R.;!Liu,!H.;!Frechet,!J.!M.!J.!Bodipy/backboned!polymers!as!
electron!donor!in!bulk!heterojunction!solar!cells.!Chem.$Commun.$2010,!46,!4148/
4150.!
(27)! Rousseau,!T.;!Cravino,!A.;!Bura,!T.;!Ulrich,!G.;!Ziessel,!R.;!Roncali,!J.!BODIPY!
derivatives!as!donor!materials!for!bulk!heterojunction!solar!cells.!Chem.$Commun.$
2009,!1673/1675.!
(28)! Rousseau,!T.;!Cravino,!A.;!Ripaud,!E.;!Leriche,!P.;!Rihn,!S.;!De!Nicola,!A.;!Ziessel,!R.;!
Roncali,!J.!A!tailored!hybrid!BODIPY/oligothiophene!donor!for!molecular!bulk!
heterojunction!solar!cells!with!improved!performances.!Chem.$Commun.$2010,!46,!
5082/5084.!
(29)! Kolemen,!S.;!Bozdemir,!O.!A.;!Cakmak,!Y.;!Barin,!G.;!Erten/Ela,!S.;!Marszalek,!M.;!Yum,!
J./H.;!Zakeeruddin,!S.!M.;!Nazeeruddin,!M.!K.;!Gratzel,!M.;!Akkaya,!E.!U.!Optimization!
of!distyryl/Bodipy!chromophores!for!efficient!panchromatic!sensitization!in!dye!
sensitized!solar!cells.!Chem.$Sci.$2011,!2,!949/954.!
(30)! Kolemen,!S.;!Cakmak,!Y.;!Erten/Ela,!S.;!Altay,!Y.;!Brendel,!J.;!Thelakkat,!M.;!Akkaya,!E.!
U.!Solid/State!Dye/Sensitized!Solar!Cells!Using!Red!and!Near/IR!Absorbing!Bodipy!
Sensitizers.!Org.$Lett.$2010,!12,!3812/3815.!
! 71!
(31)! Kubo,!Y.;!Watanabe,!K.;!Nishiyabu,!R.;!Hata,!R.;!Murakami,!A.;!Shoda,!T.;!Ota,!H.!Near/
Infrared!Absorbing!Boron/dibenzopyrromethenes!that!Serve!As!Light/Harvesting!
Sensitizers!for!Polymeric!Solar!Cells.!Org.$Lett.$2011,!13,!4574/4577.!
(32)! Hayashi,!Y.;!Obata,!N.;!Tamaru,!M.;!Yamaguchi,!S.;!Matsuo,!Y.;!Saeki,!A.;!Seki,!S.;!
Kureishi,!Y.;!Saito,!S.;!Yamaguchi,!S.;!Shinokubo,!H.!Facile!Synthesis!of!Biphenyl/
Fused!BODIPY!and!Its!Property.!Org.$Lett.$2012,!14,!866/869.!
(33)! Poe,!A.!M.;!Della!Pelle,!A.!M.;!Subrahmanyam,!A.!V.;!White,!W.;!Wantz,!G.;!
Thayumanavan,!S.!Small!molecule!BODIPY!dyes!as!non/fullerene!acceptors!in!bulk!
heterojunction!organic!photovoltaics.!Chem.$Commun.$2014,!50,!2913/2915.!
(34)! Duran/Sampedro,!G.;!Esnal,!I.;!Agarrabeitia,!A.!R.;!Bañuelos!Prieto,!J.;!Cerdán,!L.;!
García/Moreno,!I.;!Costela,!A.;!Lopez/Arbeloa,!I.;!Ortiz,!M.!J.!First!Highly!Efficient!and!
Photostable!E!and!C!Derivatives!of!4,4/Difluoro/4/bora/3a,4a/diaza/s/indacene!
(BODIPY)!as!Dye!Lasers!in!the!Liquid!Phase,!Thin!Films,!and!Solid/State!Rods.!Chem.K
Eur.$J.$2014,!20,!2646/2653.!
(35)! Ieda,!N.;!Hotta,!Y.;!Miyata,!N.;!Kimura,!K.;!Nakagawa,!H.!Photomanipulation!of!
Vasodilation!with!a!Blue/Light/Controllable!Nitric!Oxide!Releaser.!J.$Am.$Chem.$Soc.$
2014,!136,!7085/7091.!
(36)! Wang,!J.;!Zong,!Q.;!Wu,!Q.;!Shen,!J.;!Dai,!F.;!Wu,!C.!Synthesis!and!photo/property!of!2/
cyano!boron/dipyrromethene!and!the!application!for!detecting!fluoride!ion.!
Tetrahedron$2015,!71,!9611/9616.!
(37)! Krumova,!K.;!Cosa,!G.!Bodipy!Dyes!with!Tunable!Redox!Potentials!and!Functional!
Groups!for!Further!Tethering:!Preparation,!Electrochemical,!and!Spectroscopic!
Characterization.!J.$Am.$Chem.$Soc.$2010,!132,!17560/17569.!
(38)! Chu,!C./W.;!Shrotriya,!V.;!Li,!G.;!Yang,!Y.!Tuning!acceptor!energy!level!for!efficient!
charge!collection!in!copper/phthalocyanine/based!organic!solar!cells.!Appl.$Phys.$
Lett.$2006,!88,!153504.!
(39)! Wilke,!A.;!Endres,!J.;!Hormann,!U.;!Niederhausen,!J.;!Schlesinger,!R.;!Frisch,!J.;!
Amsalem,!P.;!Wagner,!J.;!Gruber,!M.;!Opitz,!A.;!Vollmer,!A.;!Brutting,!W.;!Kahn,!A.;!
Koch,!N.!Correlation!between!interface!energetics!and!open!circuit!voltage!in!
organic!photovoltaic!cells.!Appl.$Phys.$Lett.$2012,!101,!233301/4.!
(40)! Cicoira,!F.;!Santato,!C.;!Dinelli,!F.;!Murgia,!M.;!Loi,!M.!f.!u.!u.!f.!A.;!Biscarini,!F.;!
Zamboni,!R.;!Heremans,!P.;!Muccini,!M.!Morphology!and!Field/Effect/Transistor!
Mobility!in!Tetracene!Thin!Films.!Advanced$Functional$Materials\$2005,!15\,!375\/
380\.!
(41)! Bartynski,!A.!N.;!Trinh,!C.;!Panda,!A.;!Bergemann,!K.;!Lassiter,!B.!E.;!Zimmerman,!J.!D.;!
Forrest,!S.!R.;!Thompson,!M.!E.!A!Fullerene/Based!Organic!Exciton!Blocking!Layer!
with!High!Electron!Conductivity.!Nano$Lett.$2013,!13,!3315/3320.!
(42)! D’Andrade,!B.!W.;!Datta,!S.;!Forrest,!S.!R.;!Djurovich,!P.;!Polikarpov,!E.;!Thompson,!M.!
E.!Relationship!between!the!ionization!and!oxidation!potentials!of!molecular!organic!
semiconductors.!Org.$Electron.$2005,!6,!11/20.!
(43)! Djurovich,!P.!I.;!Mayo,!E.!I.;!Forrest,!S.!R.;!Thompson,!M.!E.!Measurement!of!the!
lowest!unoccupied!molecular!orbital!energies!of!molecular!organic!semiconductors.!
Org.$Electron.$2009,!10,!515/520.!
(44)! Shrotriya,!V.;!Li,!G.;!Yao,!Y.;!Moriarty,!T.;!Emery,!K.;!Yang,!Y.!Accurate!Measurement!
and!Characterization!of!Organic!Solar!Cells.!Adv.$Funct.$Mater.$2006,!16,!2016/2023.!
!
! 72!
Chapter(5.(
Synthesis(of(NearGInfrared(BODIPY(Dyes(
5.1(Introduction(
! As!discussed!in!Chapter!2,!it!is!beneficial!to!have!the!absorption!profile!of!the!active!
materials!to!be!shifted!towards!the!red!and!near/infrared!region!(NIR)!to!harness!the!
energy!of!additional!photons.!!With!respect!to!BODIPY!dyes,!a!large!library!of!NIR/
absorbing!have!been!report.
1
!!The!reported!molecules!commonly!employ!ring!extension!
across!all!sites!of!the!BODIPY!core!and!fusion!of!multiple!BODIPY!moieties.
1/9
!!However,!the!
major!application!for!most!of!these!dyes!are!focused!on!fluorescent!tagging!and!biological!
imaging!with!only!a!handful!of!these!NIR!BODIPYs!employed!as!active!materials!in!OPV.
5/6,!
10/12
!!To!continue!to!push!the!boundary!of!BODIPY/based!OPVs!and!expand!the!BODIPY!
library,!we!propose!an!additional!ring/fusion!onto!bDIP!to!produce!the!family!of!naphthyl!
BODIPY!(nDIP)!molecule!shown!in!Scheme!1.!!!The!absorption!profile!for!nDIP!molecules!
should!have!a!larger!bathochromic!shift!than!bDIP,!and!the!effects!of!the!added!π-
extension!will!be!discussed!in!this!chapter.!
!
5.2(Method(A:(RetroGDiels(Alder((
! Multiple!synthetic!pathways!have!
been!examined!for!the!synthesis!of!nDIP.!!
Method!A!is!based!on!the!analogous!Retro/
Diels!Alder!(RDA)!strategy!that!was!
successfully!employed!for!bDIP!in!Chapter!2.!!Based!on!a!similar!reported!procedure,!
Scheme(5.1(Structure(of(bDIP(and(nDIP!
! 73!
benzoquinone!is!heated!with!1,3/cyclohexadiene!to!obtained!the!desired!bicyclic!diketone!
adduct.
13
!!!The!diketone!precursor!is!than!reduced!the!diol!in!moderate!yields!followed!by!
treatment!with!POCl3!to!obtain!the!bridged!naphthalene!compound.!!It!was!transformed!
into!the!α/chloro/sulfone!by!thiophenol!and!n/chlorosuccinimide.!!The!α/chloro/sulfone!is!
converted!to!intermediate!1!in!a!single!step!following!modified!Barton/Zard!pyrrole!
synthesis!as!with!bDIP.!!1!was!purified!via!column!chromatography!and!recrystallized!to!
white!needles!in!good!yields.!!From!here,!the!pyrrole!undergoes!standard!deprotection!
with!lithium!aluminum!hydride.!!The!resulting!methyl/benzoisoindole!proceeds!through!
the!typical!BODIPY!synthesis!via!condensation!and!borylation.!!The!final!product,!RDA/
!
Figure(5.1(Synthesis(of(RDAGType(nDIP(derivatives.!Synthetic!route!for!RDA!type!precursors!to!RDA/
nDIP!intermediates!
! 74!
nDIP,!was!obtained!in!low!yield!(6%).!!The!compound!was!purified!via!column!and!heated!
up!to!250!°C!under!vacuum!for!the!removal!of!the!ethylene!bridge.!!However,!even!after!
heating!for!an!extended!amount!of!time,!the!fully!converted!product,!nDIP,!was!no!
obtained.!!Furthermore,!the!UV/VIS!absorption!spectrum!(Fig.!2a)!for!the!starting!material,!
RDA/nDIP,!shows!a!sharp!absorption!profile!common!for!BODIPY!dyes!at!530!nm,!while!the!
thermally!treated!product!showed!a!broaden!peak!and!shoulder!at!580!nm.!!While!the!
existence!of!a!bathochromic!shift!is!expected,!the!observed!shift!of!around!50!nm!is!smaller!
than!anticipated.!!With!full!aromatization!of!RDA/nDIP,!an!absorption!maximum!redder!
than!bDIP!(>!602!nm)!should!be!observed!and!the!color!of!the!solid!should!be!deep!blue.!!
However,!the!absorption!maximum!after!thermal!treatment!is!still!bluer!than!bDIP,!
indicating!the!possibility!of!incomplete!conversion.!!The!resulting!NMR!from!the!isolated!
deep!orange!compound!shows!the!incorrect!number!of!peaks!in!the!aromatic!region!while!
retaining!some!of!the!parent!RDA/nDIP!peaks.!
! In!the!second!attempt,!the!carboxylic!ester!groups!were!left!on!the!nDIP!core!to!
investigate!if!electron/withdrawing!effects!would!facilitate!the!RDA!removal!of!the!ethylene!
!
Figure(5.2(UVGVis(Absorption(of(RDAGnDIP(Before(and(After(Heating.!!The!UV/Vis!absorption!of!RDA/
nDIP!before!and!after!heating!with!bDIP!for!reference(a).!!Before!and!after!heating!for!RDA/nDIP/c!(b).!!
! 75!
bridge.!!RDA/nDIP/c!was!synthesized!in!similarly!low!yields!and!subjected!to!the!same!
thermal!experiments.!!!Unfortunately,!similar!results!were!observed!for!RDA/nDIP/c!in!the!
form!of!partial!conversion.!!!The!absorption!plot!in!Figure!2b!shows!a!maximum!at!540!nm,!
while!the!“after”!spectrum!shows!the!emergence!of!new!peaks!at!365!nm!and!590!nm.!!
Again,!though!there!is!a!bathochromic!shift,!the!final!absorption!profile!is!not!as!red!as!
expected,!indicating!that!only!one!of!the!RDA!moieties!is!removed.!!It!is!interesting!to!note!
that!the!absorption!peaks!sharpened!significantly!in!width!from!a!full!width!half!max!of!
about!70!nm!to!30!nm.!!It!is!known!that!carboxylic!ester!substituted!BODIPYs!have!general!
showed!broader!absorption!than!their!unsubstituted!counter!parts!as!in!the!case!for!bDIP!
and!bDIP/c.!!The!sharpness!is!likely!due!to!the!thermal!removal!of!carboxylic!esters!at!210!
°C.!!Thus,!the!observed!change!in!the!absorption!plot!is!a!combination!of!the!expulsion!of!
the!carboxylic!ester!and!partial!removal!of!the!ethylene!bridge.!!!Additional!heating!up!250!
°C!led!to!the!complete!decomposition!of!the!material.!!Hence,!while!the!RDA!approach!had!
worked!for!bDIP,!it!seems!that!the!ethylene!bridges!are!thermodynamically!stable!and!
unable!to!be!removed!even!at!the!decomposition!temperature!for!RDA/nDIP!and!RDA/
nDIP/c.!!
!
5.3(Method(B:(Dihydro(Intermediate(
! Utilizing!another!method!previously!applied!successfully!on!bDIP/type!molecule,!it!
is!possible!to!obtain!nDIP!through!the!oxidation!of!dihydro/nDIP!(2H/nDIP).
14
!!The!
synthetic!strategy!is!presented!in!Figure!3.!!The!first!step!involves!reducing!naphthalene!
with!sodium!to!produce!1,4/dihydro!naphthalene.!!Using!this!substrate,!the!remaining!steps!
to!the!key!dihydro/benzoisoindole!precursor,!2,!is!identical!to!the!RDA!approach!though!
! 76!
the!overall!yield!is!generally!slightly!lower!for!the!dihydro!derivatives.!!To!synthesize!the!
final!nDIP!in!one!pot,!the!typical!procedure!was!modified!with!3!equivalence!of!oxidant,!
dicyano/dichloro/benzoquinone!(DDQ),!without!isolation!of!2H/nDIP.!!To!our!surprise,!the!
obtained!product!was!still!the!unoxidized!2H/nDIP!in!10%!yield!even!though!an!excess!of!
oxidant!was!used.!!The!product!was!purified!and!isolated,!followed!by!additional!attempts!
to!oxidize!the!product!in!refluxing!dichloromethane!with!DDQ.!!When!the!heating!seemed!
insufficient!and!no!reaction!was!observed,!2H/nDIP!was!treated!with!DDQ!in!refluxing!
toluene.!!However,!both!TLC!and!NMR!showed!that!2H/nDIP!remained!completely!intact!
after!heating!from!1!to!24!hours.!
!
!
Figure(5.3(Synthesis(of(DihydroGType(nDIP(derivatives.!Synthetic!route!for!nDIP/c!via!the!dihydro!
precursor.!
! 77!
Since!metal!complexes!similar!to!nDIP/c!has!previously!been!reported,!their!
procedure!was!repeated!using!the!protected!2!as!starting!material.!!Following!nearly!
identical!conditions!as!with!2H/nDIP,!the!reaction!yielded!the!desired!product,!nDIP/c,!in!
35%,!which!is!considered!high!for!BODIPY!reactions.!!It!is!possible!that!the!carboxylic!
esters!lowered!the!oxidation!barrier!sufficiently!for!the!dihydro!intermediate!to!be!fully!
oxidized!into!the!final!product,!nDIP/c.!!Repeated!attempts!to!synthesize!the!methyl/
substituted!nDIP!were!nonetheless!unsuccessful.!!
!
5.4(Properties(of(nDIP(derivatives(
! The!photophysical!properties!of!RDA/nDIP!derivatives!are!shown!in!Figure!4a.!!
Since!both!compounds!have!the!BODIPY!cores!isolated!from!the!rest!of!the!π/system,!their!
absorption!and!emission!maxima!are!similar!to!their!unsubstituted!BODIPY!analogs!around!
520!nm.!!RDA/nDIP’s!absorption!profile!is!nearly!identical!to!RDA/bDIP!(Chapter!2.),!
suggesting!that!the!peripheral!benzene!rings!are!not!involved!in!the!optical!transitions.!
! Both!the!carboxylic!ester!containing!compounds,!RDA/nDIP/c!and!nDIP/c,!show!
broader!and!featureless!spectra!compared!to!the!parent!BODIPY.!!In!the!case!of!RDA/
derivatives,!this!difference!is!highlighted!in!Figure!4a.!!The!absorption!and!emission!traces!
for!the!RDA/nDIP/c!are!about!double!the!width!of!RDA/nDIP.!!The!effect!is!even!more!
pronounced!for!nDIP/c!where!the!high/energy!shoulder!typically!observed!next!to!the!main!
peak!is!absent,!creating!a!featureless!broad!absorption.!!A!similar!effect!of!carboxylic!ester!
has!been!previously!observed!for!bDIP!and!bDIP/c!as!well.
14
!!The!presence!of!carboxylic!
ester!introduces!vibrational!states!and!reorganization!energies!where!additional!
transitions!are!available.!!In!addition!to!broadening,!nDIP/c’s!absorption!maximum!has!
! 78!
moved!more!than!120!nm!redder!compared!to!RDA/nDIP/c.!!The!difference!highlights!the!
impact!of!the!added!π/system!on!the!BODIPY!core!on!the!electronics!of!the!molecule.!
! Cyclic!voltammograms!for!RDA/nDIP!and!RDA/nDIP/c!are!shown!in!Figure!4c!and!
!
!
Figure(5.4(Absorption(&(Emission(Plots(and(Cyclic(Voltammograms(of(nDIP(derivatives.!!Absorption!and!
emission!plot!of!the!RDA/derivatives!in!dichloromethane!(a).!!Absorption!spectrum!of!nDIP/c!in!
dichloromethane(b).!!Cyclic!voltammogram!for!RDA/nDIP/c!and!nDIP/c,!respectively,!in!acetonitrile!versus!
ferrocene.!
!
!!
λ
abs(
(nm)( E
red
((V)( E
ox
((V)( HOMO((eV)( LUMO((eV)( E
ec
((eV)(
nDIP=c( 670# 11.21# 0.34# 5.07# 3.35# 1.72#
RDA=nDIP=c( 545# 11.04# 1.35# 6.49# 3.68# 2.81#
Table(5.1(Physical(Properties(of(nDIPGc(and(RDAGnDIPGc.!!A!summary!of!physical!properties!for!nDIP/c!and!
RDA/nDIP/c,!comparing!the!effects!of!aromatized!ring/fusion!on!these!properties.!
! 79!
4d.!!While!nDIP/c!shows!two!fully!reversible!oxidations!and!reductions,!the!same!processes!
for!RDA/nDIP/c!are!not!reversible!though!the!origin!of!this!difference!has!yet!to!be!
identified.!!!The!reduction!potential!of!nDIP/c!is!0.4!V!lower!than!RDA/nDIP/c,!resulting!in!a!
slightly!shallower!LUMO!for!nDIP/c.!!The!oxidation!potential!for!RDA/nDIP/c!and!nDIP/c!are!
1.35!V!and!0.34!V,!respectively.!!The!marked!difference!in!oxidation!potential!(~1!V)!seen!
for!the!pair!is!the!direct!consequence!of!the!added!benzene!to!the!π/system.!!As!presented!
in!Table!1.,!the!HOMO!of!nDIP/c!is!significantly!destabilized!as!the!result!of!aromatization.!!
The!net!effect!is!a!1.1!eV!reduction!of!electrochemical!bandgap!(Eec)!from!RDA/nDIP/c!
(2.81!eV)!to!nDIP/c!(1.72!eV),!resulting!in!the!marked!bathochromic!shift.!
!
5.5(Conclusion!
! Various!synthetic!strategies!were!investigated!for!accessing!nDIP.!!RDA/type!
derivatives!for!nDIP!did!not!result!in!the!final!aromatization!of!the!molecule!due!to!their!
inert!reactivity!and!decomposition!upon!heating!up!to!250!°C.!!!!A!fully!oxidized!nDIP/c!was!
synthesized!via!the!2H/nDIP!intermediate!in!which!the!ethylene!bridges!of!RDA!derivatives!
were!replaced!by!2!hydrogens.!!The!conversion!is!achieved!by!using!DDQ!as!the!oxidant!to!
fully!aromatize!the!product.!!In!this!method,!nDIP/c!was!obtained!under!thermally!mild!
condition!at!room!temperature.!!When!applying!this!method!for!the!methyl!substituted,!no!
product!was!observed.!!nDIP/c!showed!a!significant!shift!in!absorption!maximum!is!
achieved!from!545!nm!of!the!unoxidized!form!to!670!nm.!!!The!electrochemical!property!of!
the!molecule!also!matches!the!absorption!change!with!calculated!HOMO/LUMO!gap!
reduced!from!2.81!eV!to!1.72!eV.!!In!summary,!π/extension!of!bDIP!to!nDIP!successfully!
red/shifts!the!absorption!maximum!yielding!a!novel!NIR/BODIPY!dye.! (
! 80!
5.6(Experimental(
Unless!noted!otherwise,!all!chemicals!were!purchased!from!Sigma/Aldrich!and!used!
without!further!purification.!!Dry!solvents!were!purified!using!a!Glass!Contour!Solvent!
System!and!all!reactions!were!performed!under!inert!nitrogen!atmosphere.!!(
UV−VIS!spectra!were!recorded!on!a!Hewlett/Packard!4853!Diode!Array!
Spectrometer.!!!Photoluminescence!spectra!were!measured!using!a!QuantaMaster!Photon!
Technology!International!fluorescence!spectrofluorometer.!!Cyclic!voltammetry!(CV)!
measurements!were!performed!using!an!EG&G!Potentiostat/Galvanostat!model!283.!!
Samples!were!run!in!0.1!M!tetra/n/butyl/ammonium!hexafluorophosphate!solution!in!
dichloromethane!purged!with!nitrogen.!!The!counter,!reference,!and!working!electrodes!
were!platinum,!silver,!and!glassy!carbon,!respectively.!!Scans!were!performed!at!100!mV/s!
and!oxidation/reduction!values!were!calibrated!to!ferrocene/ferrocenium!internal!
references.!!HOMO!and!LUMO!were!calculated!based!on!reported!methods!using!measured!
values!from!CV.
15/16
!
(
( (
! 81!
5.7(NMR(Spectra(
!
!
NH
O
a
a
b
c
d
e
f
g
h
i
NH#
f#
a#
b#c#
g#
h#
i#
e#
d#
NH
O
a
a
b
c
d
e
f
g
h
f"
b"c"
h"
g"
e"
d"
a"
NH"
! 82!
!
!
N N
B
F F
acetone'
N N
B
EtO
2
C CO
2
Et F F
! 83!
!
!
N N
B
F F
DCM$
*Crude$NMR$
N N
B
F F
CO
2
Et EtO
2
C
DCM$
! 84!
References(
!
(1)! Ni,!Y.;!Wu,!J.!Far/red!and!near!infrared!BODIPY!dyes:!synthesis!and!applications!for!
fluorescent!pH!probes!and!bio/imaging.!Org.$Biomol.$Chem.$2014,!12,!3774/3791.!
(2)! Nakamura,!M.;!Kitatsuka,!M.;!Takahashi,!K.;!Nagata,!T.;!Mori,!S.;!Kuzuhara,!D.;!
Okujima,!T.;!Yamada,!H.;!Nakae,!T.;!Uno,!H.!Yellow!NIR!dye:![small!pi]/fused!
bisbenzoBODIPYs!with!electron/withdrawing!groups.!Org.$Biomol.$Chem.$2014,!12,!
1309/1317.!
(3)! Erten/Ela,!S.;!Yilmaz,!M.!D.;!Icli,!B.;!Dede,!Y.;!Icli,!S.;!Akkaya,!E.!U.!A!Panchromatic!
Boradiazaindacene!(BODIPY)!Sensitizer!for!Dye/Sensitized!Solar!Cells.!Org.$Lett.$
2008,!10,!3299/3302.!
(4)! Hayashi,!Y.;!Obata,!N.;!Tamaru,!M.;!Yamaguchi,!S.;!Matsuo,!Y.;!Saeki,!A.;!Seki,!S.;!
Kureishi,!Y.;!Saito,!S.;!Yamaguchi,!S.;!Shinokubo,!H.!Facile!Synthesis!of!Biphenyl/
Fused!BODIPY!and!Its!Property.!Org.$Lett.$2012,!14,!866/869.!
(5)! Kubo,!Y.;!Watanabe,!K.;!Nishiyabu,!R.;!Hata,!R.;!Murakami,!A.;!Shoda,!T.;!Ota,!H.!Near/
Infrared!Absorbing!Boron/dibenzopyrromethenes!that!Serve!As!Light/Harvesting!
Sensitizers!for!Polymeric!Solar!Cells.!Org.$Lett.$2011,!13,!4574/4577.!
(6)! Rousseau,!T.;!Cravino,!A.;!Ripaud,!E.;!Leriche,!P.;!Rihn,!S.;!De!Nicola,!A.;!Ziessel,!R.;!
Roncali,!J.!A!tailored!hybrid!BODIPY/oligothiophene!donor!for!molecular!bulk!
heterojunction!solar!cells!with!improved!performances.!Chem.$Commun.$2010,!46,!
5082/5084.!
(7)! Jiao,!C.;!Huang,!K./W.;!Wu,!J.!Perylene/Fused!BODIPY!Dye!with!Near/IR!
Absorption/Emission!and!High!Photostability.!Org.$Lett.$2011,!13,!632/635.!
(8)! Kowada,!T.;!Yamaguchi,!S.;!Fujinaga,!H.;!Ohe,!K.!Near/infrared!BODIPY!dyes!
modulated!with!spirofluorene!moieties.!Tetrahedron$2011,!67,!3105/3110.!
(9)! Ulrich,!G.;!Goeb,!S.!b.;!De!Nicola,!A.;!Retailleau,!P.;!Ziessel,!R.!Chemistry!at!Boron:!
Synthesis!and!Properties!of!Red!to!Near/IR!Fluorescent!Dyes!Based!on!Boron/
Substituted!Diisoindolomethene!Frameworks.!J.$Org.$Chem.$2011,!76,!4489/4505.!
(10)! Bura,!T.;!Leclerc,!N.;!Fall,!S.;!Lévêque,!P.;!Heiser,!T.;!Retailleau,!P.;!Rihn,!S.;!Mirloup,!
A.;!Ziessel,!R.!High/Performance!Solution/Processed!Solar!Cells!and!Ambipolar!
Behavior!in!Organic!Field/Effect!Transistors!with!Thienyl/BODIPY!Scaffoldings.!J.$
Am.$Chem.$Soc.$2012,!134,!17404/17407.!
(11)! Kim,!B.;!Ma,!B.;!Donuru,!V.!R.;!Liu,!H.;!Frechet,!J.!M.!J.!Bodipy/backboned!polymers!as!
electron!donor!in!bulk!heterojunction!solar!cells.!Chem.$Commun.$2010,!46,!4148/
4150.!
(12)! Rousseau,!T.;!Cravino,!A.;!Bura,!T.;!Ulrich,!G.;!Ziessel,!R.;!Roncali,!J.!BODIPY!
derivatives!as!donor!materials!for!bulk!heterojunction!solar!cells.!Chem.$Commun.$
2009,!1673/1675.!
(13)! Finikova,!O.!S.;!Aleshchenkov,!S.!E.;!Briñas,!R.!P.;!Cheprakov,!A.!V.;!Carroll,!P.!J.;!
Vinogradov,!S.!A.!Synthesis!of!Symmetrical!Tetraaryltetranaphtho[2,3]porphyrins.!J.$
Org.$Chem.$2005,!70,!4617/4628.!
(14)! Uppal,!T.;!Hu,!X.;!Fronczek,!F.!R.;!Maschek,!S.;!Bobadova/Parvanova,!P.;!Vicente,!M.!G.!
H.!Synthesis,!Computational!Modeling,!and!Properties!of!Benzo/Appended!BODIPYs.!
Chem.KEur.$J.$2012,!18,!3893/3905.!
! 85!
(15)! D’Andrade,!B.!W.;!Datta,!S.;!Forrest,!S.!R.;!Djurovich,!P.;!Polikarpov,!E.;!Thompson,!M.!
E.!Relationship!between!the!ionization!and!oxidation!potentials!of!molecular!organic!
semiconductors.!Org.$Electron.$2005,!6,!11/20.!
(16)! Djurovich,!P.!I.;!Mayo,!E.!I.;!Forrest,!S.!R.;!Thompson,!M.!E.!Measurement!of!the!
lowest!unoccupied!molecular!orbital!energies!of!molecular!organic!semiconductors.!
Org.$Electron.$2009,!10,!515/520.!
!
! !
! 86!
Chapter(6.((
Progress(towards(MesoGLinked(BODIPY(Dimers((
6.1(Introduction(
Over!the!past!two!decades,!significant!advances!in!understand!the!fundamental!
principles!of!OPVs!have!enabled!the!efficiency!of!OPVs!to!improve!from!1%!of!the!first!
OPV
1
!to!over!9%!of!modern!OPV!technology.
3/5
!!Of!the!various!OPV!parameters!governing!
device!performance,!large!milestones!have!been!achieved!in!understanding!how!the!open/
circuit!voltage!(VOC)!is!determined!and!governed!by!organic!materials!properties.
6/7
!
Despite!these!advances,!VOC!of!both!state/of/the/art!and!most!reported!devices!have!
largely!been!pinned!below!1!V!with!relatively!fewer!reports!of!devices!breaking!the!1!V!
hurdle.
8/11
!!Tandem!devices!can!improve!VOC!to!>!1!V
11
,!but!not!all!high/performing!
tandems
12/13
!or!even!small!molecular/based!OPVs
4,!12
!are!able!to!overcome!the!1!V!barrier.!!
To!understand!how!to!better!improve!VOC,!it!is!necessary!to!understand!the!origin!of!the!
parameter.!!As!discussed!in!the!introduction,!electronic!coupling!and!ΔEDA!play!important!
roles!in!the!determination!of!VOC.!However,!it!has!been!shown!that!the!energy!of!the!charge!
transfer!state!(ECT)!is!a!better!indicator!in!predicting!and!influencing!VOC,!though!ultimately!
ECT!is!limited!by!ΔEDA.!
14/16
!!The!VOC!equation!in!Chapter!1!can!be!simplified!with!some!
assumptions!into:!
!
!"
=
!"#
!
!"
!
!"
!
!"
+ !
!
!"
!
!
,!where!ECT!replaces!as!a!factor!in!VOC.!!!Furthermore,!a!strong!empirical!relationship!
between!high!VOC!and!ECT!has!been!shown!in!the!literature
8,!15
!with!the!formula:!
! 87!
!
!"
=!
!"
−0.6$
Thus,!by!improving!ECT,!one!can!directly!increase!the!voltage!and!efficiency!of!an!OPV.!
One!approach!to!construct!a!more!favorable!energetic!landscape!is!to!utilize!the!
symmetry!breaking!charge!transfer!(SBCT)!phenomenon.!!This!process!has!been!shown!to!
be!an!essential!component!to!efficient!electron!transfer!in!molecular!chromophores!by!
quickly!localizing!opposing!charges!in!the!opposite!halves!of!a!twisted!molecule.!!In!this!
state,!the!charges!are!effectively!isolated!and!separated!with!decreased!energy!loss!and!
propensity!for!recombination!due!to!the!weakened!coupling!between!the!two!sites!of!the!
molecule!upon!excitation.
17/18
!!!This!phenomenon!enables!a!reduction!of!the!typical!~0.6!eV!
loss!observed!when!singlet!excited!state!relax!into!the!CT!state.!!In!photosystem!II!of!
photosynthetic!reaction!centers,!the!special!pair!porphyrins!exhibits!this!phenomenon!to!
shuttle!high!energy!electrons!away!with!minimal!energetic!loss.
19
!!This!ultrafast!process!is!
extremely!efficient!and!depends!on!a!cascade!of!perfectly!aligned!molecules!to!minimize!
the!energetic!cost.!!While!that!it!may!be!difficult!to!reproduce!Mother!Nature’s!degree!of!
efficiency!in!an!OPV,!simpler!systems!based!on!anthracene!and!other!small!molecules!have!
been!shown!to!exhibit!this!behavior!as!well.
2,!8,!20/21
!!In!the!bianthryl!system,!the!symmetric!
anthracene!ends!spontaneously!form!an!intramolecular!charge!transfer!state!upon!
excitation!in!polar!environment.
20
!!This!state!puts!the!cation!and!anion!on!opposite!halves!
of!the!molecule;!thus!facilitating!the!key!step!of!!charge!separation!by!spatially!isolating!the!
charges!and!hindering!recombination.!
At!the!D/A!interface!where!there!is!a!polarized!environment,!molecules!that!
undergo!SBCT!should!have!a!more!favorable!tendency!to!form!the!CT!state!at!a!lower!
kinetic!cost,!thus!enable!charge!separation!to!occur!at!a!higher!energy.!!While!inside!the!
! 88!
bulk!film!in!the!absence!of!a!polar!environment,!the!two!halves!of!the!symmetric!molecule!
behave!normally,!absorbing!photons!and!transporting!carriers.!!
The!formation!of!intramolecular!charge!transfer!(ICT)!states!has!been!observed!in!a!
variety!of!materials.
17/18
!!!Incorporating!some!of!these!molecules!into!OPVs,!this!strategy!
has!been!shown!to!improve!VOC.
8
!!Compared!to!non/SBCT!molecules,!SBCT!molecules!are!
able!to!achieve!high!VOC!of!>1.0!eV.!!One!example,!zinc!dipyrrin,!was!shown!to!achieve!a!
higher!VOC!due!a!higher!ECT!given!the!same!ΔEDA!as!C60!with!identical!donors.!!!However,!an!
unintended!loss!of!JSC!trade/off!was!still!observed.!!This!is!due!to!the!overlapping!
absorption!coverage!in!the!visible!region!of!the!acceptor!molecule!compared!to!C60.!!With!
the!success!of!preliminary!studies!and!the!current!limited!library!of!materials!to!study!
from,!it!is!essential!to!explore!additional!molecules!with!a!broader!spectrum!of!absorption!
profiles!to!improve!the!efficiency!of!OPVs.!
As!discussed!in!previous!chapters!and!in!literature,!boron!dipyrrins!have!been!
!
Scheme(6.1(SBCT(Molecules(and(Synthetic(Strategies(for(BODIPY(Dimers(
! 89!
shown!to!be!an!excellent!candidate!for!numerous!applications.
22/23
!!They!have!been!shown!
to!be!effective!chemical!sensors,!laser!emitters,!biological!imagers,!and!organic!
semiconductors!with!ever!increasing!applications.!!!Our!work!has!demonstrated!that!its!
high!absorptivity!and!chemical!versatility!makes!it!a!useful!material!to!examine!as!OPV!and!
SBCT!material.!!
Unlike!zinc!dipyrrin!where!two!ligands!naturally!coordinate!to!the!metal!center!to!
form!a!symmetric!compound,!BODIPY/based!SBCT!molecules!will!require!the!two!halves!to!
be!covalently!attached.!!Previously,!several!BODIPY!dimers!have!been!synthesized!at!the!2!
and!3!positions.
24/27
!!However,!only!dimers!linked!at!the!meso/position!(Scheme!1.)!have!
been!shown!to!undergo!SBCT!and!form!ICT!states!upon!excitation.
2
!It!was!shown!that!
direct!linkage!of!the!two!BODIPY!halves!facilitates!their!communications!through!electronic!
coupling!and!forms!ICT!states!efficiently!upon!excitation.
2
!!However,!by!adding!a!phenyl!
unit!in!the!linkage,!the!communication!is!hindered,!and!the!rate!of!ICT!formation!is!slowed.!!
Encouraged!with!these!preliminary!results,!it!is!necessary!to!examine!additional!synthetic!
strategies!in!expanding!the!BODIPY!SBCT!material!library.!!A!summary!of!synthetic!routes!
investigated!in!this!chapter!is!presented!in!Scheme!1.!
(
6.2(OneGPot(Synthesis(of(Meso#Linked(BODIPY(Dimer(
( The!first!published!procedure!for!the!synthesis!the!meso/linked!dimer,!1,!requires!
multiple!steps!resulting!in!low!a!overall!yield!that!necessitates!new!strategies!for!scaling!up!
this!novel!material.!!As!shown!in!Figure!1.,!the!original!strategy!involves!building!half!of!the!
BODIPY!dimer!first!followed!by!the!conversion!of!the!acetoxy!group!to!an!aldehyde!
functionality!in!subsequent!steps.!!The!final!product!is!obtained!when!the!intermediate!
! 90!
BODIPY!C!is!use!as!the!aldehyde!source!in!the!condensation!completed!the!second!half!of!
the!dipyrrin.!
A!simpler!method!can!be!used!with!the!replacement!of!acetoxyacetyl!chloride!with!
oxalyl!chloride!as!shown!in!Figure!2.!!In!this!method,!instead!of!performing!the!
condensation!reaction!twice,!a!single!one/pot!reaction!should!result!in!the!formation!of!the!
key!intermediate!bis/dipyrromethene,!D.!!The!addition!of!a!base!and!boron!source!under!
standard!condition!should!yield!the!desired!meso/linked!dimer.!As!shown!in!recently!
reported!procedure,!this!single!step!procedure!works!at!a!10%!yield.
28
!!Several!attempts!to!
optimize!the!reaction!conditions!to!improve!the!yield!were!unsuccessful.!!Freshly!distilled!
pyrrole,!a!variety!of!bases,!and!reagent!addition!rates!were!all!examined,!but!the!reported!
reaction!was!not!reproducible!nonetheless.!!The!resulting!by/product,!F,!was!consistently!
obtained!and!appeared!to!be!an!orange!BODIPY!with!a!pyrrole!and!ketone!adduct.!!While!
highly!emissive!with!a!BODIPY!yellow!glow,!the!by/product!showed!a!significant!Rf!value!
mismatch!when!spotted!against!1,!a!deep!magenta!colored!solid.!!Aside!from!visual!
!
Figure(6.1(First(Reported(Synthesis(of(Meso#Linked(BODIPY(Dimers.!!Original!synthetic!pathway!
for!synthesizing!meso/linked!dimers.!!The!yield!for!the!following!products!are:!A,!11%;!B,!71%;!C,!
83%;!D,!38%.
2
!
! 91!
confirmation,!both!the!NMR,!elemental!analysis,!and!mass!spectrometry!(See!NMR!section)!
revealed!that!the!by/product!closely!matches!the!structure!of!F.!!With!the!inherent!
irreproducibility!and!low!reported!yield,!this!approach!was!abandoned!in!favor!of!
alternative!strategies.!
!
6.3(Radical(Dimerization(of(BODIPY(Dyes(
( The!second!approach!examined!is!the!application!chemical!radical!dimerization!
reactions!of!cyanine!dyes.!!It!has!been!shown!that!cyanine!and!polymethine!dyes!dimerize!
readily!under!oxidative!conditions!on!even/numbered!carbons!due!to!the!electronic!
distribution!of!the!dication,!activating!those!sites!(Fig.!3).
29/31
!!BODIPY!dyes!exhibit!many!
cyanine/like!properties!and!are!structurally!similar!to!cyanine!dyes!to!apply!this!strategy.!!!
While!not!the!desired!meso/linked!dimer,!2,2’!and!1,1’!positions!dimers!have!synthesized!
!
Figure(6.2(OneGPot(Synthesis(of(Meso#Linked(BODIPY(Dimers.!!One/pot!synthesis!of!meso/linked!
dimer,!1,!and!by/product,!F.(
! 92!
under!oxidative!conditions!with!FeCl3.
25/26
!!It!is!interesting!to!note!that!in!the!case!of!
BODIPY,!both!the!1!and!2!carbon!are!able!to!dimerize!under!oxidizing!conditions!unlike!the!
even!versus!odd!system!of!cyanine!dyes.!!Upon!careful!examination!of!the!BODIPY!electron!
density!distribution!in!the!HOMO!and!LUMO!of!the!molecule,!the!difference!between!
cyanine!and!BODIPY!can!be!rationalized.!!It!is!evident!that!both!the!1!and!2!carbons!have!
significant!electronic!density!under!oxidative!conditions!in!the!HOMO!as!shown!in!Figure!
4b.!!Hence,!it!is!reasonable!that!both!sites!are!activated!and!able!to!dimerize!upon!the!
addition!of!FeCl3.!!In!Figure!4a,!Nepomnyashchii!et.$al.!are!able!to!control!the!dimer!product!
by!blocking!the!corresponding!sites!with!methyl!groups!to!yield!the!1,’1!and!2,2’!dimers.
25/
26
!!The!calculated!HOMO!also!reveal!that!it!is!not!possible!to!achieve!dimerization!through!
the!meso!or!5/position!of!BODIPY!via!oxidation!because!there!is!no!electron!density!at!that!
position.!!However,!it!is!possible!to!do!so!under!reductive!conditions!as!suggested!by!the!
presence!of!electronic!distribution!in!the!5/position!shown!in!the!LUMO!in!Figure!4b.!
! Chlorinated!BODIPYs,!clGBDP(and!clGme4GBDP,!were!synthesized!following!
Figure(6.3(Oxidative(Reaction(and(Electron(Distributions(of(Cyanine(Dyes.!Oxidative!dimerization!
of!cyanine!dyes!and!products!(a).!!The!electron!density!distribution!localized!on!even/numbered!
carbons!of!along!the!polymethine!!backbone!(b).!
! 93!
literature!procedure!shown!in!Scheme!2.
32
!!Starting!pyrroles!were!treated!with!
thiophosgene!to!obtain!the!corresponding!thioketone!percursor,!G ,!in!low!yields!as!purple!
crystals!after!purification.!!Following!treatment!with!potassium!hydroxide!and!hydrogen!
peroxide,!G !is!convert!to!dipyrrolo/ketone,!H,!as!a!yellow!solid!in!moderate!yields.!!It!is!
possible!to!by/pass!this!step!and!synthesize!H!directly!from!the!pyrrole!with!phosgene;!
however,!due!to!the!toxicity!of!phosgene,!we!have!proceeded!with!thiophosgene!as!the!
preferred!reagent!at!the!cost!of!synthetic!efficiency.!!The!ketone!is!chlorinated!with!
phosphorus!oxychloride!followed!by!borylation!with!boron!trifluoride!in!a!single!step!to!
obtain!the!desired!products,!clGBDP(and!clGme4GBDP,!as!bright!orange!crystals!after!
recrystallization!from!dichloromethane!and!hexanes.!!!As!expected,!the!unsubstituted!clG
BDP!has!a!lower!yield!to!the!absence!of!methyl!groups!to!block!side!reactions!for!pyrrole.!!
! Characterization!details!of!both!compounds!are!presented!in!Figure!5!and!Table!1.!!
The!absorption!and!emission!profiles!are!sharp!with!corresponding!maxima!with!small!
Stoke’s!shift!commonly!observed!for!BODIPY!dyes.
33
!!Both!compounds!have!similar!!
!
Figure(6.4(Oxidative(Reaction(and(Electron(Distributions(of(BODIPY(Dyes.!Oxidative!dimerization!of!
BODIPY!dyes!and!products!(a).!!The!numbering!of!carbons!and!electron!density!distribution!for!a!BODIPY!
(b).!
! 94!
! !
!
!
!
Figure(6.5(Absorption(&(Emission(Plots(and(Cyclic(Voltammograms(of(clGBDPs.!!Absorption!and!emission!
plots!as!well!as!CV!traces!for!clGBDP((a!and!c)!and!clGme4GBDP((b!and!d).!
!!
λ
abs(
(nm)( λ
em(
(nm)( Φ(
εsol((
((x(10
4
(M
=1
cm
=1
)
E
red
((V)( E
ox
((V)( E
ec
((eV)(
cl=BDP( 503# 514# 0.76# 9.8*# 10.92# 1.35# 2.27#
cl=me
4
=BDP( 502# 516# 0.79# 7.7# 11.4# 0.92# 2.32#
Table(6.1(Physical(Properties(of(clGBDP(and(clGme4GBDP.!A!summary!of!photophysical!and!electrochemical!
property!of!chlorinated!BODIPYs.!
!
! 95!
absorption!and!emission!maxima!at!around!502!nm!and!514!nm!due!to!nearly!identical!
electrochemical!gap,!Eec.!!The!redox!properties,!however,!show!a!marked!shift!due!to!the!
effect!of!the!alkyl!groups!and!have!been!previously!documented!extensively.
34
!!After!the!
addition!of!the!four!methyl!groups,!both!the!reduction!and!oxidation!potential!shift!by!
about!0.4!V,!thus!keeping!the!band!gap!constant.!
! Unfortunately,!subjecting!the!chlorinated!BODIPYs!to!reductive!conditions!did!not!
result!in!the!desired!dimer!with!multiple!reducing!agents!(Fig.!6).!!Initially,!sodium!and!
sodium!hydride!were!used.!!With!a!reduction!potential!of!/0.92!V!and!/1.4!V,!it!was!soon!
realized!that!the!brute!force!of!these!powerful!reducing!agents!(>3!V)!completely!destroyed!
the!BODIPYs.!!!We!then!selected!a!milder!reductant,!samarium!iodide,!with!a!reducing!
potential!of!2.2!V!for!the!same!experiment.
35
!!Similarly,!no!product!was!observed!for!the!
reaction.!!A!shorted!reaction!time!resulted!in!the!partial!recovery!of!the!starting!material,!
!
Figure(6.6(Reductive(Conditions(for(clGBDPs.!!Chemical!reduction!of!chlorinated!BODIPYs!with!
various!reducing!agents.!
!
Reducing(Agent( Na( SmI
2
( Cobaltocene(
E
red
#vs.#Fc/Fc
+#
(V)# 13.35# 12.15# 11.33#
Table(6.2(Reduction(Potential(of(Reducing(Agents.(!Reduction!potentials!of!the!reducing!agents!
examined!for!anionic!radical!dimerization.!
! 96!
but!no!dimeric!product!was!able!to!be!isolated.!!It!is!possible!that!BODIPY/type!simply!
cannot!dimerize!under!reductive!conditions.!!However,!it!may!be!worthwhile!to!use!
cobaltocene!as!the!reducing!agent!even!though!it’s!Ered!(1.33!V)!is!slightly!lower,!but!the!
risk!of!over/reduction!can!be!minimized.!
!
6.4(Palladium(CrossGCoupling(BODIPY(Precursors((
( With!access!to!halogenated!BODIPY,!it!is!logical!to!pursue!intermediates!that!are!
capable!of!undergoing!palladium!cross!couplings!by!converting!the!chlorides!to!boronic!
acids.!!The!prevalence!and!usefulness!of!palladium!coupling!reactions!should!be!a!reliable!
strategy!to!synthesize!BODIPY!dimers.!!Furthermore,!plenty!of!halogenated!BODIPYs!have!
been!synthesized!at!all!available!positions!of!the!pyrrole!on!the!BODIPY!core.
36/40
!!However,!
only!two!boronic!acid!derivatives!have!been!reported!at!the!carbon!1!and!2!positions.
41/42
!!
Aside!from!a!phenyl/boronic!acid!that!has!been!synthesized,!no!direct!boronic!acid!
derivatives!at!the!meso/position!has!been!reported.
43/44
!!Therefore,!it!will!be!insightful!to!
provide!these!substrates!to!directly!couple!with!mesoKhalogenated!BODIPYs!to!synthesize!
BODIPY!dimers.!
! Various!synthetic!conditions!and!results!are!summarized!in!Scheme!3.!!In!reaction!A,!
our!first!attempt!was!to!synthesize!the!dimer!in!one!step!by!using!half!an!equivalence!of!
bis(pinacol/diboron)!and!promoting!inKsitu!homocoupling!of!the!clGBDP.!!However,!no!
product!was!observed!and!a!fully!unsubstituted!BODIPY!core!was!isolated!and!confirmed!
by!NMR.!!Thus,!we!proceeded!to!approach!the!problem!in!a!more!step/wise!fashion!to!
isolate!the!desired!boronic!acid!product!via!reaction!D!and!F!in!Scheme!3.!!Subjecting!both!
clGBDP!and!clGme4GBDP!to!standard!conditions!for!boronic!acid!synthesis!again!did!not!
! 97!
result!in!any!product.
45/46
!!Our!results!suggest!that!the!meso/chloride!may!be!too!unreactive!
to!proceed!in!this!type!of!reaction.!!It!has!been!shown!that!substituting!the!chloride!with!
either!iodide!or!bromide!significantly!improve!these!type!of!reactions.
47
!!Following!a!
reported!procedure!in!reaction!B,!sodium!iodide!was!reacted!with!for!an!halide!exchange!
reaction!in!freshly!distilled!acetone,!but!no!iodide!product!was!recovered.!!Chemical!shifts!
for!all!methyl!peaks!were!identical!to!the!clGme4GBDP,!and!a!mass!spec!of!the!isolated!
compound!showed!the!mass!of!clGme4GBDP.!!The!bromide!derivative!was!then!synthesized!
by!replacing!phosphorus!oxychloride!with!phosphorus!oxybromide!in!low!yields!(12%).!!!
The!bromide/substituted!BODIPY,!brGBDP,!was!also!incapable!in!accessing!the!boronic!acid!
derivatives.!!During!reaction!preparation,!decomposition!of!the!brGBDP!was!observed!upon!
the!addition!of!a!base.!!The!yellow/orange!emissive!solution!quickly!turned!to!a!dull!green!
after!stirring.!!Additional!experiments!with!chloride!derivatives!also!show!that!they!are!
also!unstable!under!various!basic!conditions!in!Figure!7.!!It!seems!that!only!the!directly!
Scheme(6.3(Synthetic(Conditions(for(Pd(CrossGCoupling(BODIPY(Precursors!
! 98!
halogenated!BODIPYs!are!sensitive!to!bases,!while!phenyl/bridged!compounds!at!the!meso/
position!are!insensitive.!!With!this!in!mind,!reactions!were!set!up!with!base!added!last!into!
the!reaction!flask!after!all!other!reagents!have!been!added.!!Despite!this!effort,!BODIPY!
boronic!acids!could!not!be!identified!in!the!crude!NMR.!
! While!no!successful!attempts!were!achieved!in!the!synthesis!of!meso/boronic!acid!
BODIPYs,!useful!knowledge!was!still!learned!regarding!halogenated!BODIPYs!and!their!
stability.!!It!will!be!worthwhile!to!further!investigate!coupling!reactions!for!alternative!
systems!such!as!the!tin/based!Stille!Coupling.!
!
!
!
Figure(6.7(Stability(of(BODIPY(Compounds(in(Basic(Conditions.!!Reaction!mixtures!of!cl/BDP!in!
solution!with!various!bases!(top).!Reaction!mixture!of!BODIPY!compounds!in!solution!with!potassium!
acetate!(bottom).!
!
! 99!
6.5(BiphenylGBridged(BODIPY(Dimers(
! In!the!previous!section,!it!was!shown!that!if!the!halide!or!boronic!acid!moiety!is!
attached!to!the!BODIPY!molecule!through!a!phenyl!ring,!the!resulting!BODIPY!derivatives!
are!stable!under!basic!conditions.!!A!series!of!these!molecules!were!prepared!as!shown!in!
Figure!8.!!No!additional!optimization!conditions!for!the!synthesis!of!boronic!acid!
derivatives!were!attempted,!but!the!yields!for!K!and!M!were!consistently!low!at!less!than!
5%.!!!Opened!positions!on!the!pyrrole!rings!may!be!the!origin!of!the!low!yields!and!render!
K!and!M!to!be!more!susceptible!to!side!reactions!since!the!fully!blocked!BODIPY,!L,!showed!
!
Figure(6.8(Molecular(Structure(and(yields(of(BiphenylGBridged(BODIPY(Dimer.((Molecular!
structure!and!yields!for!coupling!intermediate!and!biphenyl/bridged!dimers.!
! 100!
a!doubling!of!product!yield.!!Corresponding!halogenated!BODIPYs!had!higher!yields!at!
around!10%,!but!were!still!plagued!by!relatively!low!yields.!
In!lieu!of!synthesizing!directly!linked!dimers,!biphenyl/bridged!dimers!were!
successful!synthesized!following!standard!Suzuki!coupling!conditions.!!As!presented!in!
Figure!8,!three!dimers!were!synthesized!in!moderate!yields!with!dimer!2!and!3!
asymmetrically!constructed,!while!dimer!4!is!a!symmetrical!molecule!across!the!biphenyl!
bridge.!!NMR!and!elemental!analyses!confirmed!their!identity!and!purity.!
Given!the!substantial!increased!in!the!distance!between!the!BODIPY!cores,!these!
molecules!may!exhibit!weak!to!no!SBCT!upon!excitation.!!Nonetheless,!it!will!still!be!
interesting!to!fully!characterize!these!molecules!and!synthesize!additional!derivatives!to!
investigate!the!correlation!among!SBCT!activity,!intramolecular!coupling,!and!bridging!
distance.!
!
6.6(Conclusion(
! Multiple!synthetic!approaches!were!investigated!for!making!the!meso/linked!dimer,!
1.!!Conventional!methods!were!successful!in!accessing!this!molecule!even!though!it!
resulted!in!multiple!steps!or!low!yields.!!One/pot!synthesis!of!1!was!unsuccessful!due!to!
incomplete!linkage!of!all!for!pyrrole!units!as!well!as!major!side!reactions.!!Though!BODIPY!
dyes!are!similar!to!cyanine!dyes,!the!anionic!radical!dimerization!approach!under!reducing!
conditions!does!not!transfer!to!the!class!of!BODIPY!molecules.!!Oxidative!conditions!do!
result!in!dimers,!but!not!the!meso/linked!molecule!that!undergoes!SBCT.!!Attempts!to!
synthesized!mesoKboronic!acid!BODIPY!derivatives!were!unsuccessful!under!various!
optimization!conditions.!!It!was!found!that!meso/halides!are!not!stable!under!the!basic!
! 101!
conditions!of!palladium/catalyzed!cross/coupling!reactions.!!Finally,!with!the!knowledge!
that!phenyl/bridged!boronic!acid!and!halides!are!stable!in!cross/coupling!reactions,!three!
biphenyl/bridged!dimers!were!synthesized.!!While!they!are!not!directly!linked,!it!will!be!
interesting!to!study!the!long!range!electronic!coupling!effects!between!the!two!BODIPY!
halves!and!investigate!the!degree!of!symmetry!breaking!in!these!molecules.!
!
6.7(Experimental(
Unless!noted!otherwise,!all!chemicals!were!purchased!from!Sigma/Aldrich!and!used!
without!further!purification.!!Dry!solvents!were!purified!using!a!Glass!Contour!Solvent!
System!and!all!reactions!were!performed!under!inert!nitrogen!atmosphere.!!NMR!spectra!
were!recorded!on!a!Varian!400!NMR!spectrometer!and!referenced!to!the!residual!proton!
resonance!of!chloroform!(CDCl3)!solvent!at!7.26!ppm( (
! 102!
6.8(NMR(Spectra(
!!
!
!
DCM$
N N
Cl
B
F
2
N N
Br
B
F F
! 103!
!!
!
!!
N N
Cl
B
F
2
N N
B
F
2
NH
O
m/z: 370 (exp.); 369.18(calc.)
Elemental Analysis:
Calc.: C, 65.06; H, 6.01; N, 11.38
Exp.: C, 64.33; H, 6.17;, N, 11.05
! 104!
!!
!
!!
N
B
N
F F
B
O O
N
B
N
F F
Br
! 105!
!
!
!
N
B
N
F F
Br
N
B
N
F F
B
O O
! 106!
!!
!
!
N
B
N
F F
B
O O
DCM$
N
B
N
N
B
N
F F
F F
Elemental Analysis:
Calc.: C, 71.81; H, 6.31; N, 7.98
Exp.: C, 71.00; H, 6.40; N, 7.81
! 107!
!
!!
!
! !
N
B
N
N
B
N
F F
F F
Elemental Analysis:
Calc.: C, 70.61; H, 5.61; N, 8.67
Exp.: C, 70.11; H, 5.74; N, 8.47
N
B
N
N
B
N
F F
F F
! 108!
References(
(
(1)! Tang,!C.!W.!Two layer!organic!photovoltaic!cell.!Appl.$Phys.$Lett.$1986,!48,!183/185.!
(2)! Whited,!M.!T.;!Patel,!N.!M.;!Roberts,!S.!T.;!Allen,!K.;!Djurovich,!P.!I.;!Bradforth,!S.!E.;!
Thompson,!M.!E.!Symmetry/Breaking!Intramolecular!Charge!Transfer!in!the!Excited!
State!of!meso/Linked!BODIPY!Dyads.!Chem.$Commun.$2011,!Submitted.!
(3)! He,!Z.;!Xiao,!B.;!Liu,!F.;!Wu,!H.;!Yang,!Y.;!Xiao,!S.;!Wang,!C.;!Russell,!T.!P.;!Cao,!Y.!Single/
junction!polymer!solar!cells!with!high!efficiency!and!photovoltage.!Nat$Photon$
2015,!9,!174/179.!
(4)! Zhang,!Q.;!Kan,!B.;!Liu,!F.;!Long,!G.;!Wan,!X.;!Chen,!X.;!Zuo,!Y.;!Ni,!W.;!Zhang,!H.;!Li,!M.;!
Hu,!Z.;!Huang,!F.;!Cao,!Y.;!Liang,!Z.;!Zhang,!M.;!Russell,!T.!P.;!Chen,!Y.!Small/molecule!
solar!cells!with!efficiency!over!9%.!Nat$Photon$2015,!9,!35/41.!
(5)! Zhao,!W.;!Qian,!D.;!Zhang,!S.;!Li,!S.;!Inganäs,!O.;!Gao,!F.;!Hou,!J.!Fullerene/Free!
Polymer!Solar!Cells!with!over!11%!Efficiency!and!Excellent!Thermal!Stability.!Adv.$
Mater.$2016,!28,!4734/4739.!
(6)! Schlenker,!C.!W.;!Thompson,!M.!E.!The!molecular!nature!of!photovoltage!losses!in!
organic!solar!cells.!Chem.$Commun.$2011,!47,!3702/3716.!
(7)! Elumalai,!N.!K.;!Uddin,!A.!Open!circuit!voltage!of!organic!solar!cells:!an!in/depth!
review.!Energy$&$Environmental$Science$2016,!9,!391/410.!
(8)! Bartynski,!A.!N.;!Gruber,!M.;!Das,!S.;!Rangan,!S.;!Mollinger,!S.;!Trinh,!C.;!Bradforth,!S.!
E.;!Vandewal,!K.;!Salleo,!A.;!Bartynski,!R.!A.;!Bruetting,!W.;!Thompson,!M.!E.!
Symmetry/Breaking!Charge!Transfer!in!a!Zinc!Chlorodipyrrin!Acceptor!for!High!
Open!Circuit!Voltage!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2015,!137,!5397/5405.!
(9)! Jørgensen,!M.;!Carlé,!J.!E.;!Søndergaard,!R.!R.;!Lauritzen,!M.;!Dagnæs/Hansen,!N.!A.;!
Byskov,!S.!L.;!Andersen,!T.!R.;!Larsen/Olsen,!T.!T.;!Böttiger,!A.!P.!L.;!Andreasen,!B.;!Fu,!
L.;!Zuo,!L.;!Liu,!Y.;!Bundgaard,!E.;!Zhan,!X.;!Chen,!H.;!Krebs,!F.!C.!The!state!of!organic!
solar!cells—A!meta!analysis.!Sol.$Energy$Mater.$Sol.$Cells$2013,!119,!84/93.!
(10)! Peng,!Y.;!Zhang,!L.;!Andrew,!T.!L.!High!open/circuit!voltage,!high!fill!factor!single/
junction!organic!solar!cells.!Appl.$Phys.$Lett.$2014,!105,!083304.!
(11)! You,!J.;!Dou,!L.;!Yoshimura,!K.;!Kato,!T.;!Ohya,!K.;!Moriarty,!T.;!Emery,!K.;!Chen,!C./C.;!
Gao,!J.;!Li,!G.;!Yang,!Y.!A!polymer!tandem!solar!cell!with!10.6%!power!conversion!
efficiency.!Nature$Communications\$2013,!4\,!1446\.!
(12)! Cnops,!K.;!Rand,!B.!P.;!Cheyns,!D.;!Verreet,!B.;!Empl,!M.!A.;!Heremans,!P.!8.4%!
efficient!fullerene/free!organic!solar!cells!exploiting!long/range!exciton!energy!
transfer.!Nat$Commun$2014,!5,!1/6.!
(13)! Gao,!Y.;!Jin,!F.;!Li,!W.;!Su,!Z.;!Chu,!B.;!Wang,!J.;!Zhao,!H.;!Wu,!H.;!Liu,!C.;!Hou,!F.;!Lin,!T.;!
Song,!Q.!Highly!efficient!organic!tandem!solar!cell!with!a!SubPc!interlayer!based!on!
TAPC:C70!bulk!heterojunction.!Scientific$Reports\$2016,!6\,!23916\.!
(14)! Erwin,!P.;!Thompson,!M.!E.!Elucidating!the!interplay!between!dark!current!coupling!
and!open!circuit!voltage!in!organic!photovoltaics.!Appl.$Phys.$Lett.$2011,!98,!/.!
(15)! Graham,!K.!R.;!Erwin,!P.;!Nordlund,!D.;!Vandewal,!K.;!Li,!R.;!Ngongang!Ndjawa,!G.!O.;!
Hoke,!E.!T.;!Salleo,!A.;!Thompson,!M.!E.;!McGehee,!M.!D.;!Amassian,!A.!Re/evaluating!
the!Role!of!Sterics!and!Electronic!Coupling!in!Determining!the!Open/Circuit!Voltage!
of!Organic!Solar!Cells.!Adv.$Mater.$2013,!25,!6076/6082.!
! 109!
(16)! Perez,!M.!D.;!Borek,!C.;!Forrest,!S.!R.;!Thompson,!M.!E.!Molecular!and!Morphological!
Influences!on!the!Open!Circuit!Voltages!of!Organic!Photovoltaic!Devices.!J.$Am.$Chem.$
Soc.$2009,!131,!9281/9286.!
(17)! Grabowski,!Z.!R.;!Rotkiewicz,!K.;!Rettig,!W.!Structural!Changes!Accompanying!
Intramolecular!Electron!Transfer: !Focus!on!Twisted!Intramolecular!Charge/
Transfer!States!and!Structures.!Chem.$Rev.$2003,!103,!3899/4032.!
(18)! Rettig,!W.!Charge!Separation!in!Excited!States!of!Decoupled!Systems—TICT!
Compounds!and!Implications!Regarding!the!Development!of!New!Laser!Dyes!and!
the!Primary!Process!of!Vision!and!Photosynthesis.!Angewandte$Chemie$International$
Edition$in$English$1986,!25,!971/988.!
(19)! Senge,!M.;!Ryan,!A.;!Letchford,!K.;!MacGowan,!S.;!Mielke,!T.!Chlorophylls,!Symmetry,!
Chirality,!and!Photosynthesis.!Symmetry$2014,!6,!781.!
(20)! Schneider,!F.;!Lippert,!E.!Elektronenspektren!und!Elektronenstruktur!von!9,9'/
Dianthryl.!Berichte$der$Bunsengesellschaft$für$physikalische$Chemie$1968,!72,!1155/
1160.!
(21)! Trinh,!C.;!Kirlikovali,!K.;!Das,!S.;!Ener,!M.!E.;!Gray,!H.!B.;!Djurovich,!P.;!Bradforth,!S.!E.;!
Thompson,!M.!E.!Symmetry/Breaking!Charge!Transfer!of!Visible!Light!Absorbing!
Systems:!Zinc!Dipyrrins.!The$Journal$of$Physical$Chemistry$C$2014,!118,!21834/
21845.!
(22)! Benstead,!M.;!Mehl,!G.!H.;!Boyle,!R.!W.!4,4 /Difluoro/4/bora/3a,4a/diaza/s/
indacenes!(BODIPYs)!as!components!of!novel!light!active!materials.!Tetrahedron$
2011,!67,!3573/3601.!
(23)! Ulrich,!G.;!Ziessel,!R.;!Harriman,!A.!The!Chemistry!of!Fluorescent!Bodipy!Dyes:!
Versatility!Unsurpassed.!Angew.$Chem.,$Int.$Ed.$2008,!47,!1184/1201.!
(24)! Coskun,!A.;!Akkaya,!E.!U.!Ion!Sensing!Coupled!to!Resonance!Energy!Transfer: !A!
Highly!Selective!and!Sensitive!Ratiometric!Fluorescent!Chemosensor!for!Ag(I)!by!a!
Modular!Approach.!J.$Am.$Chem.$Soc.$2005,!127,!10464/10465.!
(25)! Nepomnyashchii,.A..B.;.Bröring,.M.;.Ahrens,.J.;.Bard,.A..J..Synthesis,.Photophysical,.
Electrochemical,!and!Electrogenerated!Chemiluminescence!Studies.!Multiple!
Sequential!Electron!Transfers!in!BODIPY!Monomers,!Dimers,!Trimers,!and!Polymer.!
J.$Am.$Chem.$Soc.$2011,!133,!8633/8645.!
(26)! Nepomnyashchii,!A.!B.;!Bröring,!M.;!Ahrens,!J.;!Bard,!A.!J.!Chemical!and!
Electrochemical!Dimerization!of!BODIPY!Compounds:!Electrogenerated!
Chemiluminescent!Detection!of!Dimer!Formation.!J.$Am.$Chem.$Soc.$2011,!133,!
19498/19504.!
(27)! Rihn,!S.;!Erdem,!M.;!De!Nicola,!A.;!Retailleau,!P.;!Ziessel,!R.!Phenyliodine(III)!
Bis(trifluoroacetate)!(PIFA)/Promoted!Synthesis!of!Bodipy!Dimers!Displaying!
Unusual!Redox!Properties.!Org.$Lett.$2011,!13,!1916/1919.!
(28)! Wang,!L.;!Cao,!J.;!Wang,!J./w.;!Chen,!Q.;!Cui,!A./j.;!He,!M./y.!Facile!synthesis!of!dimeric!
BODIPY!and!its!catalytic!activity!for!sulfide!oxidation!under!visible!light.!RSC$
Advances$2014,!4,!14786/14790.!
(29)! Lenhard,!J.!R.;!Hein,!B.!R.;!Muenter,!A.!A.!Redox!limitations!for!the!spectral!
sensitization!of!silver!halide!in!the!infrared.!The$Journal$of$Physical$Chemistry$1993,!
97,!8269/8280.!
! 110!
(30)! Lenhard,!J.!R.;!Parton,!R.!L.!Electrochemical!and!spectroscopic!analyses!of!the!
thermodynamics!of!the!reversible!dimerization!of!cyanine!radical!dications.!J.$Am.$
Chem.$Soc.$1987,!109,!5808/5813.!
(31)! Parton,!R.!L.;!Lenhard,!J.!R.!Dimerization!reactions!of!cyanine!radical!dications.!J.$Org.$
Chem.$1990,!55,!49/57.!
(32)! Leen,!V.;!Yuan,!P.;!Wang,!L.;!Boens,!N.;!Dehaen,!W.!Synthesis!of!Meso/Halogenated!
BODIPYs!and!Access!to!Meso/Substituted!Analogues.!Org.$Lett.$2012,!14,!6150/6153.!
(33)! Loudet,!A.;!Burgess,!K.!BODIPY!Dyes!and!Their!Derivatives: !Syntheses!and!
Spectroscopic!Properties.!Chem.$Rev.$2007,!107,!4891/4932.!
(34)! Nepomnyashchii,!A.!B.;!Bard,!A.!J.!Electrochemistry!and!Electrogenerated!
Chemiluminescence!of!BODIPY!Dyes.!Acc.$Chem.$Res.$2012,!45,!1844/1853.!
(35)! Molander,!G.!A.;!Harris,!C.!R.,!Samarium(II)!Iodide.!In!Encyclopedia$of$Reagents$for$
Organic$Synthesis,!John!Wiley!&!Sons,!Ltd:!2001.!
(36)! Chen,!Y.;!Zhao,!J.;!Guo,!H.;!Xie,!L.!Geometry!Relaxation/Induced!Large!Stokes!Shift!in!
Red/Emitting!Borondipyrromethenes!(BODIPY)!and!Applications!in!Fluorescent!
Thiol!Probes.!J.$Org.$Chem.$2012,!77,!2192/2206.!
(37)! Hafuka,!A.;!Kando,!R.;!Ohya,!K.;!Yamada,!K.;!Okabe,!S.;!Satoh,!H.!Substituent!Effects!at!
the!5/Position!of!3/[Bis(pyridine/2/ylmethyl)amino]/BODIPY!Cation!Sensor!Used!for!
Ratiometric!Quantification!of!Cu²⁺.!Bull.$Chem.$Soc.$Jpn.$2015,!88,!447/
454.!
(38)! Jiao,!L.;!Pang,!W.;!Zhou,!J.;!Wei,!Y.;!Mu,!X.;!Bai,!G.;!Hao,!E.!Regioselective!Stepwise!
Bromination!of!Boron!Dipyrromethene!(BODIPY)!Dyes.!J.$Org.$Chem.$2011,!76,!
9988/9996.!
(39)! Peña/Cabrera,!E.;!Aguilar/Aguilar,!A.;!González/Domínguez,!M.;!Lager,!E.;!Zamudio/
Vázquez,!R.;!Godoy/Vargas,!J.;!Villanueva/García,!F.!Simple,!General,!and!Efficient!
Synthesis!of!Meso/Substituted!Borondipyrromethenes!from!a!Single!Platform.!Org.$
Lett.$2007,!9,!3985/3988.!
(40)! Zhao,!N.;!Xuan,!S.;!Fronczek,!F.!R.;!Smith,!K.!M.;!Vicente,!M.!G.!H.!Stepwise!
Polychlorination!of!8/Chloro/BODIPY!and!Regioselective!Functionalization!of!
2,3,5,6,8/Pentachloro/BODIPY.!J.$Org.$Chem.$2015,!80,!8377/8383.!
(41)! Huynh,!A.!M.;!Menges,!J.;!Vester,!M.;!Dier,!T.;!Huch,!V.;!Volmer,!D.!A.;!Jung,!G.!
Monofluorination!and!Trifluoromethylation!of!BODIPY!Dyes!for!Prolonged!Single/
Molecule!Detection.!ChemPhysChem$2016,!17,!433/442.!
(42)! Sekiya,!M.;!Umezawa,!K.;!Sato,!A.;!Citterio,!D.;!Suzuki,!K.!A!novel!luciferin/based!
bright!chemiluminescent!probe!for!the!detection!of!reactive!oxygen!species.!Chem.$
Commun.$2009,!3047/3049.!
(43)! Sugimoto,!H.;!Muto,!M.;!Tanaka,!T.;!Osuka,!A.!Synthesis!of!BODIPY/Appended!
Subporphyrins.!Eur.$J.$Org.$Chem.$2011,!2011,!71/77.!
(44)! Zhai,!J.;!Pan,!T.;!Zhu,!J.;!Xu,!Y.;!Chen,!J.;!Xie,!Y.;!Qin,!Y.!Boronic!Acid!Functionalized!
Boron!Dipyrromethene!Fluorescent!Probes:!Preparation,!Characterization,!and!
Saccharides!Sensing!Applications.!Anal.$Chem.$2012,!84,!10214/10220.!
(45)! Duong,!H.!A.;!Chua,!S.;!Huleatt,!P.!B.;!Chai,!C.!L.!L.!Synthesis!of!Biindolyls!via!
Palladium/Catalyzed!Reactions.!J.$Org.$Chem.$2008,!73,!9177/9180.!
(46)! Ishiyama,!T.;!Murata,!M.;!Miyaura,!N.!Palladium(0)/Catalyzed!Cross/Coupling!
Reaction!of!Alkoxydiboron!with!Haloarenes:!A!Direct!Procedure!for!Arylboronic!
Esters.!J.$Org.$Chem.$1995,!60,!7508/7510.!
! 111!
(47)! Leen,!V.;!Miscoria,!D.;!Yin,!S.;!Filarowski,!A.;!Molisho!Ngongo,!J.;!Van!der!Auweraer,!
M.;!Boens,!N.;!Dehaen,!W.!1,7/Disubstituted!Boron!Dipyrromethene!(BODIPY)!Dyes:!
Synthesis!and!Spectroscopic!Properties.!J.$Org.$Chem.$2011,!76,!8168/8176.!
!
! !
! 112!
Bibliography(
(
!
(1)! Whited,!M.!T.;!Patel,!N.!M.;!Roberts,!S.!T.;!Allen,!K.;!Djurovich,!P.!I.;!Bradforth,!S.!E.;!
Thompson,!M.!E.!Symmetry/Breaking!Intramolecular!Charge!Transfer!in!the!Excited!
State!of!meso/Linked!BODIPY!Dyads.!Chem.$Commun.$2011,!Submitted.!
(2)! Darling,!S.!B.;!You,!F.!The!case!for!organic!photovoltaics.!RSC$Advances$2013,!3,!
17633/17648.!
(3)! Tang,!C.!W.!Two layer!organic!photovoltaic!cell.!Appl.$Phys.$Lett.$1986,!48,!183/185.!
(4)! Chen,!Y.;!Wan,!X.;!Long,!G.!High!Performance!Photovoltaic!Applications!Using!
Solution/Processed!Small!Molecules.!Acc.$Chem.$Res.$2013.!
(5)! Hains,!A.!W.;!Liang,!Z.;!Woodhouse,!M.!A.;!Gregg,!B.!A.!Molecular!Semiconductors!in!
Organic!Photovoltaic!Cells.!Chem.$Rev.$2010,!110,!6689/6735.!
(6)! Mishra,!A.;!Bäuerle,!P.!Small!Molecule!Organic!Semiconductors!on!the!Move:!
Promises!for!Future!Solar!Energy!Technology.!Angew.$Chem.,$Int.$Ed.$2012,!51,!2020/
2067.!
(7)! Lin,!Y.;!Li,!Y.;!Zhan,!X.!Small!molecule!semiconductors!for!high/efficiency!organic!
photovoltaics.!Chem.$Soc.$Rev.$2012,!41,!4245/4272.!
(8)! Zhou,!J.;!Zuo,!Y.;!Wan,!X.;!Long,!G.;!Zhang,!Q.;!Ni,!W.;!Liu,!Y.;!Li,!Z.;!He,!G.;!Li,!C.;!Kan,!B.;!
Li,!M.;!Chen,!Y.!Solution/Processed!and!High/Performance!Organic!Solar!Cells!Using!
Small!Molecules!with!a!Benzodithiophene!Unit.!J.$Am.$Chem.$Soc.$2013,!135,!8484/
8487.!
(9)! Kyaw,!A.!K.!K.;!Wang,!D.!H.;!Gupta,!V.;!Leong,!W.!L.;!Ke,!L.;!Bazan,!G.!C.;!Heeger,!A.!J.!
Intensity!Dependence!of!Current–Voltage!Characteristics!and!Recombination!in!
High/Efficiency!Solution/Processed!Small/Molecule!Solar!Cells.!ACS$Nano$2013,!7,!
4569/4577.!
(10)! Cnops,!K.;!Rand,!B.!P.;!Cheyns,!D.;!Verreet,!B.;!Empl,!M.!A.;!Heremans,!P.!8.4%!
efficient!fullerene/free!organic!solar!cells!exploiting!long/range!exciton!energy!
transfer.!Nat$Commun$2014,!5,!1/6.!
(11)! Schlenker,!C.!W.;!Thompson,!M.!E.!The!molecular!nature!of!photovoltage!losses!in!
organic!solar!cells.!Chem.$Commun.$2011,!47,!3702/3716.!
(12)! Erwin,!P.;!Thompson,!M.!E.!Elucidating!the!interplay!between!dark!current!coupling!
and!open!circuit!voltage!in!organic!photovoltaics.!Appl.$Phys.$Lett.$2011,!98,!/.!
(13)! Perez,!M.!D.;!Borek,!C.;!Forrest,!S.!R.;!Thompson,!M.!E.!Molecular!and!Morphological!
Influences!on!the!Open!Circuit!Voltages!of!Organic!Photovoltaic!Devices.!J.$Am.$Chem.$
Soc.$2009,!131,!9281/9286.!
(14)! Benstead,!M.;!Mehl,!G.!H.;!Boyle,!R.!W.!4,4 /Difluoro/4/bora/3a,4a/diaza/s/
indacenes!(BODIPYs)!as!components!of!novel!light!active!materials.!Tetrahedron$
2011,!67,!3573/3601.!
(15)! Ulrich,!G.;!Ziessel,!R.;!Harriman,!A.!The!Chemistry!of!Fluorescent!Bodipy!Dyes:!
Versatility!Unsurpassed.!Angew.$Chem.,$Int.$Ed.$2008,!47,!1184/1201.!
(16)! Loudet,!A.;!Burgess,!K.!BODIPY!Dyes!and!Their!Derivatives: !Syntheses!and!
Spectroscopic!Properties.!Chem.$Rev.$2007,!107,!4891/4932.!
! 113!
(17)! Shen,!Z.;!Röhr,!H.;!Rurack,!K.;!Uno,!H.;!Spieles,!M.;!Schulz,!B.;!Reck,!G.;!Ono,!N.!Boron–
Diindomethene!(BDI)!Dyes!and!Their!Tetrahydrobicyclo!Precursors—en!Route!to!a!
New!Class!of!Highly!Emissive!Fluorophores!for!the!Red!Spectral!Range.!Chem.K Eur.$J.$
2004,!10,!4853/4871.!
(18)! Uppal,!T.;!Hu,!X.;!Fronczek,!F.!R.;!Maschek,!S.;!Bobadova/Parvanova,!P.;!Vicente,!M.!G.!
H.!Synthesis,!Computational!Modeling,!and!Properties!of!Benzo/Appended!BODIPYs.!
Chem.K Eur.$J.$2012,!18,!3893/3905.!
(19)! Claret,!F.;!Carrupt,!P./A.;!Vogel,!P.!Regioselective!Electrophilic!Additions!of!
Bicyclo[2.2.n]alk/2/enes!Controlled!by!Remote!Epoxide!Functions.!Helv.$Chim.$Acta$
1987,!70,!1886/1896.!
(20)! Kang,!D./J.!E.,!Da/Han;!Mo,!Jun/Tae;!Kim,!Hyun/Seok;!Sokkalingam,!Punidha;!Lee,!
Chang/Hee;!Lee,!Phil/Ho!Synthesis!of!BODIPY!Chromophores!Bearing!Fused/
Carbocycles.!Bull.$Korean$Chem.$Soc.$2010,!31,!507/510.!
(21)! Mikhaleva,!A.!I.;!Shmidt,!E.!Y.;!Protsuk,!N.!I.;!Zorina,!N.!V.;!Trofimov,!B.!A.!Effect!of!
alkali!metal!cations!on!the!synthesis!of!4,5,6,7/tetrahydroindole!and!its!vinyl!
derivative!from!cyclohexanone!oxime!and!acetylene!in!MOH/DMSO!systems.!Dokl.$
Chem.$2008,!423,!273/275.!
(22)! Nishiki,!M.;!Oi,!W.;!Ito,!K.!Anion!binding!properties!of!indolylmethanes.!J.$Inclusion$
Phenom.$Macrocyclic$Chem.$2008,!61,!61/69.!
(23)! D’Andrade,!B.!W.;!Datta,!S.;!Forrest,!S.!R.;!Djurovich,!P.;!Polikarpov,!E.;!Thompson,!M.!
E.!Relationship!between!the!ionization!and!oxidation!potentials!of!molecular!organic!
semiconductors.!Org.$Electron.$2005,!6,!11/20.!
(24)! Djurovich,!P.!I.;!Mayo,!E.!I.;!Forrest,!S.!R.;!Thompson,!M.!E.!Measurement!of!the!
lowest!unoccupied!molecular!orbital!energies!of!molecular!organic!semiconductors.!
Org.$Electron.$2009,!10,!515/520.!
(25)! Wilke,!A.;!Endres,!J.;!Hormann,!U.;!Niederhausen,!J.;!Schlesinger,!R.;!Frisch,!J.;!
Amsalem,!P.;!Wagner,!J.;!Gruber,!M.;!Opitz,!A.;!Vollmer,!A.;!Brutting,!W.;!Kahn,!A.;!
Koch,!N.!Correlation!between!interface!energetics!and!open!circuit!voltage!in!
organic!photovoltaic!cells.!Appl.$Phys.$Lett.$2012,!101,!233301/4.!
(26)! Ni,!Y.;!Zeng,!W.;!Huang,!K./W.;!Wu,!J.!Benzene/fused!BODIPYs:!synthesis!and!the!
impact!of!fusion!mode.!Chem.$Commun.$2013,!49,!1217/1219.!
(27)! Wakamiya,!A.;!Murakami,!T.;!Yamaguchi,!S.!Benzene/fused!BODIPY!and!fully/fused!
BODIPY!dimer:!impacts!of!the!ring/fusing!at!the!b!bond!in!the!BODIPY!skeleton.!
Chem.$Sci.$2013,!4,!1002/1007.!
(28)! Hanson,!K.;!Roskop,!L.;!Djurovich,!P.!I.;!Zahariev,!F.;!Gordon,!M.!S.;!Thompson,!M.!E.!A!
Paradigm!for!Blue/!or!Red/Shifted!Absorption!of!Small!Molecules!Depending!on!the!
Site!of!π/Extension.!J.$Am.$Chem.$Soc.$2010,!132,!16247/16255.!
(29)! Momeni,!M.!R.;!Brown,!A.!Why!Do!TD/DFT!Excitation!Energies!of!BODIPY/Aza/
BODIPY!Families!Largely!Deviate!from!Experiment?!Answers!from!Electron!
Correlated!and!Multireference!Methods.!J.$Chem.$Theory$Comput.$2015,!11,!2619/
2632.!
(30)! Okujima,!T.;!Jin,!G.;!Hashimoto,!Y.;!Yamada,!H.;!Uno,!H.;!Ono,!N.!Synthesis!of!4,7/
Dihydro/2H/isoindole!Derivatives!via!Diels/Alder!Reaction!of!Tosylacetylene.!
Heterocycles$2006,!70,!619!/!626.!
! 114!
(31)! Sarma,!T.;!Panda,!P.!K.;!Setsune,!J./i.!Bis/naphthobipyrrolylmethene!derived!BODIPY!
complex:!an!intense!near/infrared!fluorescent!dye.!Chem.$Commun.$2013,!49,!9806/
9808.!
(32)! Ulrich,!G.;!Goeb,!S.!b.;!De!Nicola,!A.;!Retailleau,!P.;!Ziessel,!R.!Chemistry!at!Boron:!
Synthesis!and!Properties!of!Red!to!Near/IR!Fluorescent!Dyes!Based!on!Boron/
Substituted!Diisoindolomethene!Frameworks.!J.$Org.$Chem.$2011,!76,!4489/4505.!
(33)! Kowada,!T.;!Yamaguchi,!S.;!Fujinaga,!H.;!Ohe,!K.!Near/infrared!BODIPY!dyes!
modulated!with!spirofluorene!moieties.!Tetrahedron$2011,!67,!3105/3110.!
(34)! Jiao,!C.;!Huang,!K./W.;!Wu,!J.!Perylene/Fused!BODIPY!Dye!with!Near/IR!
Absorption/Emission!and!High!Photostability.!Org.$Lett.$2011,!13,!632/635.!
(35)! Kim,!B.;!Ma,!B.;!Donuru,!V.!R.;!Liu,!H.;!Frechet,!J.!M.!J.!Bodipy/backboned!polymers!as!
electron!donor!in!bulk!heterojunction!solar!cells.!Chem.$Commun.$2010,!46,!4148/
4150.!
(36)! Kubo,!Y.;!Watanabe,!K.;!Nishiyabu,!R.;!Hata,!R.;!Murakami,!A.;!Shoda,!T.;!Ota,!H.!Near/
Infrared!Absorbing!Boron/dibenzopyrromethenes!that!Serve!As!Light/Harvesting!
Sensitizers!for!Polymeric!Solar!Cells.!Org.$Lett.$2011,!13,!4574/4577.!
(37)! Kolemen,!S.;!Bozdemir,!O.!A.;!Cakmak,!Y.;!Barin,!G.;!Erten/Ela,!S.;!Marszalek,!M.;!Yum,!
J./H.;!Zakeeruddin,!S.!M.;!Nazeeruddin,!M.!K.;!Gratzel,!M.;!Akkaya,!E.!U.!Optimization!
of!distyryl/Bodipy!chromophores!for!efficient!panchromatic!sensitization!in!dye!
sensitized!solar!cells.!Chem.$Sci.$2011,!2,!949/954.!
(38)! Rousseau,!T.;!Cravino,!A.;!Ripaud,!E.;!Leriche,!P.;!Rihn,!S.;!De!Nicola,!A.;!Ziessel,!R.;!
Roncali,!J.!A!tailored!hybrid!BODIPY/oligothiophene!donor!for!molecular!bulk!
heterojunction!solar!cells!with!improved!performances.!Chem.$Commun.$2010,!46,!
5082/5084.!
(39)! Poe,!A.!M.;!Della!Pelle,!A.!M.;!Subrahmanyam,!A.!V.;!White,!W.;!Wantz,!G.;!
Thayumanavan,!S.!Small!molecule!BODIPY!dyes!as!non/fullerene!acceptors!in!bulk!
heterojunction!organic!photovoltaics.!Chem.$Commun.$2014,!50,!2913/2915.!
(40)! Bura,!T.;!Leclerc,!N.;!Fall,!S.;!Lévêque,!P.;!Heiser,!T.;!Retailleau,!P.;!Rihn,!S.;!Mirloup,!
A.;!Ziessel,!R.!High/Performance!Solution/Processed!Solar!Cells!and!Ambipolar!
Behavior!in!Organic!Field/Effect!Transistors!with!Thienyl/BODIPY!Scaffoldings.!J.$
Am.$Chem.$Soc.$2012,!134,!17404/17407.!
(41)! Taima,!T.;!Chikamatsu,!M.;!Bera,!R.!N.;!Yoshida,!Y.;!Saito,!K.;!Yase,!K.!Insertion!of!Thin!
Interlayers!under!the!Negative!Electrode!of!C60!Schottky/Type!Photovoltaic!Cells.!J.$
Phys.$Chem.$B$2003,!108,!1/3.!
(42)! Wang,!S.;!Mayo,!E.!I.;!Perez,!M.!D.;!Griffe,!L.;!Wei,!G.;!Djurovich,!P.!I.;!Forrest,!S.!R.;!
Thompson,!M.!E.!High!efficiency!organic!photovoltaic!cells!based!on!a!vapor!
deposited!squaraine!donor.!Appl.$Phys.$Lett.$2009,!94,!233304/3.!
(43)! Collins,!B.!A.;!Gann,!E.;!Guignard,!L.;!He,!X.;!McNeill,!C.!R.;!Ade,!H.!Molecular!
Miscibility!of!Polymer−Fullerene!Blends.!J.$Phys.$Chem.$Lett.$2010,!1,!3160/3166.!
(44)! Ma,!W.;!Tumbleston,!J.!R.;!Wang,!M.;!Gann,!E.;!Huang,!F.;!Ade,!H.!Domain!Purity,!
Miscibility,!and!Molecular!Orientation!at!Donor/Acceptor!Interfaces!in!High!
Performance!Organic!Solar!Cells:!Paths!to!Further!Improvement.!Adv.$Energy$Mater.$
2013,!3,!864/872.!
(45)! Treat,!N.!D.;!Brady,!M.!A.;!Smith,!G.;!Toney,!M.!F.;!Kramer,!E.!J.;!Hawker,!C.!J.;!
Chabinyc,!M.!L.!Interdiffusion!of!PCBM!and!P3HT!Reveals!Miscibility!in!a!
Photovoltaically!Active!Blend.!Adv.$Energy$Mater.$2011,!1,!82/89.!
! 115!
(46)! Treat,!N.!D.;!Varotto,!A.;!Takacs,!C.!J.;!Batara,!N.;!Al/Hashimi,!M.;!Heeney,!M.!J.;!
Heeger,!A.!J.;!Wudl,!F.;!Hawker,!C.!J.;!Chabinyc,!M.!L.!Polymer/Fullerene!Miscibility:!A!
Metric!for!Screening!New!Materials!for!High/Performance!Organic!Solar!Cells.!J.$Am.$
Chem.$Soc.$2012,!134,!15869/15879.!
(47)! Giovanna,!F./C.!Neutron!reflectivity!at!the!solid/liquid!interface:!examples!of!
applications!in!biophysics.!J.$Phys.:$Condens.$Matter$2001,!13,!4973.!
(48)! Ott,!F.,!Neutron!Reflectivity.!In!Surface$Science$Techniques,!Bracco,!G.;!Holst,!B.,!Eds.!
Springer!Berlin!Heidelberg:!2013;!Chapter!11,!pp!307/332.!
(49)! Russell,!T.!P.!X/ray!and!neutron!reflectivity!for!the!investigation!of!polymers.!Mater.$
Sci.$Rep.$1990,!5,!171/271.!
(50)! Zhou,!X./L.;!Chen,!S./H.!Theoretical!foundation!of!X/ray!and!neutron!reflectometry.!
Phys.$Rep.$1995,!257,!223/348.!
(51)! Kienzle,!P.!A.;!O'Donovan,!K.!V.;!Ankner,!J.!F.;!Berk,!N.!F.;!Majkrzak,!C.!F.!NIST!Center!
for!Neutron!Research!Reflectometry!Software.!http://www.ncnr.nist.gov/reflpak/.!
(52)! Xue,!J.;!Rand,!B.!P.;!Uchida,!S.;!Forrest,!S.!R.!A!Hybrid!Planar–Mixed!Molecular!
Heterojunction!Photovoltaic!Cell.!Adv.$Mater.$2005,!17,!66/71.!
(53)! Ojala,!A.;!Burckstummer,!H.;!Hwang,!J.;!Graf,!K.;!von!Vacano,!B.;!Meerholz,!K.;!Erk,!P.;!
Wurthner,!F.!Planar,!bulk!and!hybrid!merocyanine/C60!heterojunction!devices:!a!
case!study!on!thin!film!morphology!and!photovoltaic!performance.!J.$Mater.$Chem.$
2012,!22,!4473/4482.!
(54)! Peumans,!P.;!Uchida,!S.;!Forrest,!S.!R.!Efficient!bulk!heterojunction!photovoltaic!cells!
using!small/molecular/weight!organic!thin!films.!Nature$2003,!425,!158/162.!
(55)! Hiramoto,!M.;!Suemori,!K.;!Yokoyama,!M.!Photovoltaic!Properties!of!
Ultramicrostructure/Controlled!Organic!Co/Deposited!Films.!Jpn.$J.$Appl.$Phys.$2002,!
41,!2763.!
(56)! Walker,!B.;!Tamayo,!A.!B.;!Dang,!X./D.;!Zalar,!P.;!Seo,!J.!H.;!Garcia,!A.;!Tantiwiwat,!M.;!
Nguyen,!T./Q.!Nanoscale!Phase!Separation!and!High!Photovoltaic!Efficiency!in!
Solution/Processed,!Small/Molecule!Bulk!Heterojunction!Solar!Cells.!Adv.$Funct.$
Mater.$2009,!19,!3063/3069.!
(57)! Schünemann,!C.;!Wynands,!D.;!Wilde,!L.;!Hein,!M.!P.;!Pfützner,!S.;!Elschner,!C.;!
Eichhorn,!K./J.;!Leo,!K.;!Riede,!M.!Phase!separation!analysis!of!bulk!heterojunctions!
in!small/molecule!organic!solar!cells!using!zinc/phthalocyanine!and!C60.!Phys.$Rev.$B$
2012,!85,!245314.!
(58)! Khlyabich,!P.!P.;!Burkhart,!B.;!Rudenko,!A.!E.;!Thompson,!B.!C.!Optimization!and!
simplification!of!polymer–fullerene!solar!cells!through!polymer!and!active!layer!
design.!Polymer$2013,!54,!5267/5298.!
(59)! Bartynski,!A.!N.;!Trinh,!C.;!Panda,!A.;!Bergemann,!K.;!Lassiter,!B.!E.;!Zimmerman,!J.!D.;!
Forrest,!S.!R.;!Thompson,!M.!E.!A!Fullerene/Based!Organic!Exciton!Blocking!Layer!
with!High!Electron!Conductivity.!Nano$Lett.$2013,!13,!3315/3320.!
(60)! Kazaoui,!S.;!Minami,!N.;!Tanabe,!Y.;!Byrne,!H.!J.;!Eilmes,!A.;!Petelenz,!P.!
Comprehensive!analysis!of!intermolecular!charge/transfer!excited!states!in!C60!and!
C70!films.!Phys.$Rev.$B$1998,!58,!7689/7700.!
(61)! Shrotriya,!V.;!Li,!G.;!Yao,!Y.;!Moriarty,!T.;!Emery,!K.;!Yang,!Y.!Accurate!Measurement!
and!Characterization!of!Organic!Solar!Cells.!Adv.$Funct.$Mater.$2006,!16,!2016/2023.!
(62)! Facchetti,!A.!Polymer!donor–polymer!acceptor!(all/polymer)!solar!cells.!Materials$
Today$2013,!16,!123/132.!
! 116!
(63)! Kim,!Y.;!Lim,!E.!Development!of!Polymer!Acceptors!for!Organic!Photovoltaic!Cells.!
Polymers$2014,!6,!382.!
(64)! Lin,!Y.;!Zhan,!X.!Non/fullerene!acceptors!for!organic!photovoltaics:!an!emerging!
horizon.!Materials$Horizons$2014,!1,!470/488.!
(65)! Dutton,!G.!J.;!Robey,!S.!W.!Non/fullerene!acceptors:!exciton!dissociation!with!PTCDA!
versus!C60.!Phys.$Chem.$Chem.$Phys.$2015,!17,!15953/15962.!
(66)! Zhao,!D.;!Wu,!Q.;!Cai,!Z.;!Zheng,!T.;!Chen,!W.;!Lu,!J.;!Yu,!L.!Electron!Acceptors!Based!on!
α/Substituted!Perylene!Diimide!(PDI)!for!Organic!Solar!Cells.!Chem.$Mater.$2016,!28,!
1139/1146.!
(67)! Zhao,!W.;!Qian,!D.;!Zhang,!S.;!Li,!S.;!Inganäs,!O.;!Gao,!F.;!Hou,!J.!Fullerene/Free!
Polymer!Solar!Cells!with!over!11%!Efficiency!and!Excellent!Thermal!Stability.!Adv.$
Mater.$2016,!28,!4734/4739.!
(68)! Chochos,!C.!L.;!Economopoulos,!S.!P.;!Deimede,!V.;!Gregoriou,!V.!G.;!Lloyd,!M.!T.;!
Malliaras,!G.!G.;!Kallitsis,!J.!K.!Synthesis!of!a!Soluble!n/Type!Cyano!Substituted!
Polythiophene!Derivative: !A!Potential!Electron!Acceptor!in!Polymeric!Solar!Cells.!
The$Journal$of$Physical$Chemistry$C$2007,!111,!10732/10740.!
(69)! Halls,!J.!J.!M.;!Walsh,!C.!A.;!Greenham,!N.!C.;!Marseglia,!E.!A.;!Friend,!R.!H.;!Moratti,!S.!
C.;!Holmes,!A.!B.!Efficient!photodiodes!from!interpenetrating!polymer!networks.!
Nature$1995,!376,!498/500.!
(70)! Vijayakumar,!C.;!Saeki,!A.;!Seki,!S.!Optoelectronic!Properties!of!Dicyanofluorene/
Based!n/Type!Polymers.!Chemistry$–$An$Asian$Journal$2012,!7,!1845/1852.!
(71)! Yu,!G.;!Heeger,!A.!J.!Charge!separation!and!photovoltaic!conversion!in!polymer!
composites!with!internal!donor/acceptor!heterojunctions.!J.$Appl.$Phys.$1995,!78,!
4510/4515.!
(72)! Lim,!Y./F.;!Shu,!Y.;!Parkin,!S.!R.;!Anthony,!J.!E.;!Malliaras,!G.!G.!Soluble!n/type!
pentacene!derivatives!as!novel!acceptors!for!organic!solar!cells.!J.$Mater.$Chem.$
2009,!19,!3049/3056.!
(73)! Schwenn,!P.!E.;!Gui,!K.;!Nardes,!A.!M.;!Krueger,!K.!B.;!Lee,!K.!H.;!Mutkins,!K.;!
Rubinstein/Dunlop,!H.;!Shaw,!P.!E.;!Kopidakis,!N.;!Burn,!P.!L.;!Meredith,!P.!A!Small!
Molecule!Non/fullerene!Electron!Acceptor!for!Organic!Solar!Cells.!Adv.$Energy$Mater.$
2011,!1,!73/81.!
(74)! Shu,!Y.;!Lim,!Y./F.;!Li,!Z.;!Purushothaman,!B.;!Hallani,!R.;!Kim,!J.!E.;!Parkin,!S.!R.;!
Malliaras,!G.!G.;!Anthony,!J.!E.!A!survey!of!electron/deficient!pentacenes!as!acceptors!
in!polymer!bulk!heterojunction!solar!cells.!Chem.$Sci.$2011,!2,!363/368.!
(75)! Woo,!C.!H.;!Holcombe,!T.!W.;!Unruh,!D.!A.;!Sellinger,!A.;!Fréchet,!J.!M.!J.!Phenyl!vs!
Alkyl!Polythiophene:!A!Solar!Cell!Comparison!Using!a!Vinazene!Derivative!as!
Acceptor.!Chem.$Mater.$2010,!22,!1673/1679.!
(76)! Zhou,!T.;!Jia,!T.;!Kang,!B.;!Li,!F.;!Fahlman,!M.;!Wang,!Y.!Nitrile/Substituted!QA!
Derivatives:!New!Acceptor!Materials!for!Solution/Processable!Organic!Bulk!
Heterojunction!Solar!Cells.!Adv.$Energy$Mater.$2011,!1,!431/439.!
(77)! Zhou,!Y.;!Ding,!L.;!Shi,!K.;!Dai,!Y./Z.;!Ai,!N.;!Wang,!J.;!Pei,!J.!A!Non/Fullerene!Small!
Molecule!as!Efficient!Electron!Acceptor!in!Organic!Bulk!Heterojunction!Solar!Cells.!
Adv.$Mater.$2012,!24,!957/961.!
(78)! Lin,!Y.;!Zhao,!F.;!He,!Q.;!Huo,!L.;!Wu,!Y.;!Parker,!T.!C.;!Ma,!W.;!Sun,!Y.;!Wang,!C.;!Zhu,!D.;!
Heeger,!A.!J.;!Marder,!S.!R.;!Zhan,!X.!High/Performance!Electron!Acceptor!with!
! 117!
Thienyl!Side!Chains!for!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2016,!138,!4955/
4961.!
(79)! Bartynski,!A.!N.;!Gruber,!M.;!Das,!S.;!Rangan,!S.;!Mollinger,!S.;!Trinh,!C.;!Bradforth,!S.!
E.;!Vandewal,!K.;!Salleo,!A.;!Bartynski,!R.!A.;!Bruetting,!W.;!Thompson,!M.!E.!
Symmetry/Breaking!Charge!Transfer!in!a!Zinc!Chlorodipyrrin!Acceptor!for!High!
Open!Circuit!Voltage!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2015,!137,!5397/5405.!
(80)! Trinh,!C.;!Kirlikovali,!K.!O.;!Bartynski,!A.!N.;!Tassone,!C.!J.;!Toney,!M.!F.;!Burkhard,!G.!
F.;!McGehee,!M.!D.;!Djurovich,!P.!I.;!Thompson,!M.!E.!Efficient!Energy!Sensitization!of!
C60!and!Application!to!Organic!Photovoltaics.!J.$Am.$Chem.$Soc.$2013,!135,!11920/
11928.!
(81)! Chen,!J.!J.;!Conron,!S.!M.;!Erwin,!P.;!Dimitriou,!M.;!McAlahney,!K.;!Thompson,!M.!E.!
High/Efficiency!BODIPY/Based!Organic!Photovoltaics.!ACS$Appl.$Mater.$Interfaces$
2015,!7,!662/669.!
(82)! Rousseau,!T.;!Cravino,!A.;!Bura,!T.;!Ulrich,!G.;!Ziessel,!R.;!Roncali,!J.!BODIPY!
derivatives!as!donor!materials!for!bulk!heterojunction!solar!cells.!Chem.$Commun.$
2009,!1673/1675.!
(83)! Kolemen,!S.;!Cakmak,!Y.;!Erten/Ela,!S.;!Altay,!Y.;!Brendel,!J.;!Thelakkat,!M.;!Akkaya,!E.!
U.!Solid/State!Dye/Sensitized!Solar!Cells!Using!Red!and!Near/IR!Absorbing!Bodipy!
Sensitizers.!Org.$Lett.$2010,!12,!3812/3815.!
(84)! Hayashi,!Y.;!Obata,!N.;!Tamaru,!M.;!Yamaguchi,!S.;!Matsuo,!Y.;!Saeki,!A.;!Seki,!S.;!
Kureishi,!Y.;!Saito,!S.;!Yamaguchi,!S.;!Shinokubo,!H.!Facile!Synthesis!of!Biphenyl/
Fused!BODIPY!and!Its!Property.!Org.$Lett.$2012,!14,!866/869.!
(85)! Duran/Sampedro,!G.;!Esnal,!I.;!Agarrabeitia,!A.!R.;!Bañuelos!Prieto,!J.;!Cerdán,!L.;!
García/Moreno,!I.;!Costela,!A.;!Lopez/Arbeloa,!I.;!Ortiz,!M.!J.!First!Highly!Efficient!and!
Photostable!E!and!C!Derivatives!of!4,4/Difluoro/4/bora/3a,4a/diaza/s/indacene!
(BODIPY)!as!Dye!Lasers!in!the!Liquid!Phase,!Thin!Films,!and!Solid/State!Rods.!Chem.K
Eur.$J.$2014,!20,!2646/2653.!
(86)! Ieda,!N.;!Hotta,!Y.;!Miyata,!N.;!Kimura,!K.;!Nakagawa,!H.!Photomanipulation!of!
Vasodilation!with!a!Blue/Light/Controllable!Nitric!Oxide!Releaser.!J.$Am.$Chem.$Soc.$
2014,!136,!7085/7091.!
(87)! Wang,!J.;!Zong,!Q.;!Wu,!Q.;!Shen,!J.;!Dai,!F.;!Wu,!C.!Synthesis!and!photo/property!of!2/
cyano!boron/dipyrromethene!and!the!application!for!detecting!fluoride!ion.!
Tetrahedron$2015,!71,!9611/9616.!
(88)! Krumova,!K.;!Cosa,!G.!Bodipy!Dyes!with!Tunable!Redox!Potentials!and!Functional!
Groups!for!Further!Tethering:!Preparation,!Electrochemical,!and!Spectroscopic!
Characterization.!J.$Am.$Chem.$Soc.$2010,!132,!17560/17569.!
(89)! Chu,!C./W.;!Shrotriya,!V.;!Li,!G.;!Yang,!Y.!Tuning!acceptor!energy!level!for!efficient!
charge!collection!in!copper/phthalocyanine/based!organic!solar!cells.!Appl.$Phys.$
Lett.$2006,!88,!153504.!
(90)! Cicoira,!F.;!Santato,!C.;!Dinelli,!F.;!Murgia,!M.;!Loi,!M.!f.!u.!u.!f.!A.;!Biscarini,!F.;!
Zamboni,!R.;!Heremans,!P.;!Muccini,!M.!Morphology!and!Field/Effect/Transistor!
Mobility!in!Tetracene!Thin!Films.!Advanced$Functional$Materials\$2005,!15\,!375\/
380\.!
(91)! Ni,!Y.;!Wu,!J.!Far/red!and!near!infrared!BODIPY!dyes:!synthesis!and!applications!for!
fluorescent!pH!probes!and!bio/imaging.!Org.$Biomol.$Chem.$2014,!12,!3774/3791.!
! 118!
(92)! Nakamura,!M.;!Kitatsuka,!M.;!Takahashi,!K.;!Nagata,!T.;!Mori,!S.;!Kuzuhara,!D.;!
Okujima,!T.;!Yamada,!H.;!Nakae,!T.;!Uno,!H.!Yellow!NIR!dye:![small!pi]/fused!
bisbenzoBODIPYs!with!electron/withdrawing!groups.!Org.$Biomol.$Chem.$2014,!12,!
1309/1317.!
(93)! Erten/Ela,!S.;!Yilmaz,!M.!D.;!Icli,!B.;!Dede,!Y.;!Icli,!S.;!Akkaya,!E.!U.!A!Panchromatic!
Boradiazaindacene!(BODIPY)!Sensitizer!for!Dye/Sensitized!Solar!Cells.!Org.$Lett.$
2008,!10,!3299/3302.!
(94)! Finikova,!O.!S.;!Aleshchenkov,!S.!E.;!Briñas,!R.!P.;!Cheprakov,!A.!V.;!Carroll,!P.!J.;!
Vinogradov,!S.!A.!Synthesis!of!Symmetrical!Tetraaryltetranaphtho[2,3]porphyrins.!J.$
Org.$Chem.$2005,!70,!4617/4628.!
(95)! He,!Z.;!Xiao,!B.;!Liu,!F.;!Wu,!H.;!Yang,!Y.;!Xiao,!S.;!Wang,!C.;!Russell,!T.!P.;!Cao,!Y.!Single/
junction!polymer!solar!cells!with!high!efficiency!and!photovoltage.!Nat$Photon$
2015,!9,!174/179.!
(96)! Zhang,!Q.;!Kan,!B.;!Liu,!F.;!Long,!G.;!Wan,!X.;!Chen,!X.;!Zuo,!Y.;!Ni,!W.;!Zhang,!H.;!Li,!M.;!
Hu,!Z.;!Huang,!F.;!Cao,!Y.;!Liang,!Z.;!Zhang,!M.;!Russell,!T.!P.;!Chen,!Y.!Small/molecule!
solar!cells!with!efficiency!over!9%.!Nat$Photon$2015,!9,!35/41.!
(97)! Elumalai,!N.!K.;!Uddin,!A.!Open!circuit!voltage!of!organic!solar!cells:!an!in/depth!
review.!Energy$&$Environmental$Science$2016,!9,!391/410.!
(98)! Jørgensen,!M.;!Carlé,!J.!E.;!Søndergaard,!R.!R.;!Lauritzen,!M.;!Dagnæs/Hansen,!N.!A.;!
Byskov,!S.!L.;!Andersen,!T.!R.;!Larsen/Olsen,!T.!T.;!Böttiger,!A.!P.!L.;!Andreasen,!B.;!Fu,!
L.;!Zuo,!L.;!Liu,!Y.;!Bundgaard,!E.;!Zhan,!X.;!Chen,!H.;!Krebs,!F.!C.!The!state!of!organic!
solar!cells—A!meta!analysis.!Sol.$Energy$Mater.$Sol.$Cells$2013,!119,!84/93.!
(99)! Peng,!Y.;!Zhang,!L.;!Andrew,!T.!L.!High!open/circuit!voltage,!high!fill!factor!single/
junction!organic!solar!cells.!Appl.$Phys.$Lett.$2014,!105,!083304.!
(100)! You,!J.;!Dou,!L.;!Yoshimura,!K.;!Kato,!T.;!Ohya,!K.;!Moriarty,!T.;!Emery,!K.;!Chen,!C./C.;!
Gao,!J.;!Li,!G.;!Yang,!Y.!A!polymer!tandem!solar!cell!with!10.6%!power!conversion!
efficiency.!Nature$Communications\$2013,!4\,!1446\.!
(101)! Gao,!Y.;!Jin,!F.;!Li,!W.;!Su,!Z.;!Chu,!B.;!Wang,!J.;!Zhao,!H.;!Wu,!H.;!Liu,!C.;!Hou,!F.;!Lin,!T.;!
Song,!Q.!Highly!efficient!organic!tandem!solar!cell!with!a!SubPc!interlayer!based!on!
TAPC:C70!bulk!heterojunction.!Scientific$Reports\$2016,!6\,!23916\.!
(102)! Graham,!K.!R.;!Erwin,!P.;!Nordlund,!D.;!Vandewal,!K.;!Li,!R.;!Ngongang!Ndjawa,!G.!O.;!
Hoke,!E.!T.;!Salleo,!A.;!Thompson,!M.!E.;!McGehee,!M.!D.;!Amassian,!A.!Re/evaluating!
the!Role!of!Sterics!and!Electronic!Coupling!in!Determining!the!Open/Circuit!Voltage!
of!Organic!Solar!Cells.!Adv.$Mater.$2013,!25,!6076/6082.!
(103)! Grabowski,!Z.!R.;!Rotkiewicz,!K.;!Rettig,!W.!Structural!Changes!Accompanying!
Intramolecular!Electron!Transfer: !Focus!on!Twisted!Intramolecular!Charge/
Transfer!States!and!Structures.!Chem.$Rev.$2003,!103,!3899/4032.!
(104)! Rettig,!W.!Charge!Separation!in!Excited!States!of!Decoupled!Systems—TICT!
Compounds!and!Implications!Regarding!the!Development!of!New!Laser!Dyes!and!
the!Primary!Process!of!Vision!and!Photosynthesis.!Angewandte$Chemie$International$
Edition$in$English$1986,!25,!971/988.!
(105)! Senge,!M.;!Ryan,!A.;!Letchford,!K.;!MacGowan,!S.;!Mielke,!T.!Chlorophylls,!Symmetry,!
Chirality,!and!Photosynthesis.!Symmetry$2014,!6,!781.!
(106)! Schneider,!F.;!Lippert,!E.!Elektronenspektren!und!Elektronenstruktur!von!9,9'/
Dianthryl.!Berichte$der$Bunsengesellschaft$für$physikalische$Chemie$1968,!72,!1155/
1160.!
! 119!
(107)! Trinh,!C.;!Kirlikovali,!K.;!Das,!S.;!Ener,!M.!E.;!Gray,!H.!B.;!Djurovich,!P.;!Bradforth,!S.!E.;!
Thompson,!M.!E.!Symmetry/Breaking!Charge!Transfer!of!Visible!Light!Absorbing!
Systems:!Zinc!Dipyrrins.!The$Journal$of$Physical$Chemistry$C$2014,!118,!21834/
21845.!
(108)! Coskun,!A.;!Akkaya,!E.!U.!Ion!Sensing!Coupled!to!Resonance!Energy!Transfer: !A!
Highly!Selective!and!Sensitive!Ratiometric!Fluorescent!Chemosensor!for!Ag(I)!by!a!
Modular!Approach.!J.$Am.$Chem.$Soc.$2005,!127,!10464/10465.!
(109)! Nepomnyashchii,!A.!B.;!Bröring,(M.;(Ahrens,(J.;(Bard,(A.(J.(Synthesis,(Photophysical,(
Electrochemical,!and!Electrogenerated!Chemiluminescence!Studies.!Multiple!
Sequential!Electron!Transfers!in!BODIPY!Monomers,!Dimers,!Trimers,!and!Polymer.!
J.$Am.$Chem.$Soc.$2011,!133,!8633/8645.!
(110)! Nepomnyashchii,!A.!B.;!Bröring,!M.;!Ahrens,!J.;!Bard,!A.!J.!Chemical!and!
Electrochemical!Dimerization!of!BODIPY!Compounds:!Electrogenerated!
Chemiluminescent!Detection!of!Dimer!Formation.!J.$Am.$Chem.$Soc.$2011,!133,!
19498/19504.!
(111)! Rihn,!S.;!Erdem,!M.;!De!Nicola,!A.;!Retailleau,!P.;!Ziessel,!R.!Phenyliodine(III)!
Bis(trifluoroacetate)!(PIFA)/Promoted!Synthesis!of!Bodipy!Dimers!Displaying!
Unusual!Redox!Properties.!Org.$Lett.$2011,!13,!1916/1919.!
(112)! Wang,!L.;!Cao,!J.;!Wang,!J./w.;!Chen,!Q.;!Cui,!A./j.;!He,!M./y.!Facile!synthesis!of!dimeric!
BODIPY!and!its!catalytic!activity!for!sulfide!oxidation!under!visible!light.!RSC$
Advances$2014,!4,!14786/14790.!
(113)! Lenhard,!J.!R.;!Hein,!B.!R.;!Muenter,!A.!A.!Redox!limitations!for!the!spectral!
sensitization!of!silver!halide!in!the!infrared.!The$Journal$of$Physical$Chemistry$1993,!
97,!8269/8280.!
(114)! Lenhard,!J.!R.;!Parton,!R.!L.!Electrochemical!and!spectroscopic!analyses!of!the!
thermodynamics!of!the!reversible!dimerization!of!cyanine!radical!dications.!J.$Am.$
Chem.$Soc.$1987,!109,!5808/5813.!
(115)! Parton,!R.!L.;!Lenhard,!J.!R.!Dimerization!reactions!of!cyanine!radical!dications.!J.$Org.$
Chem.$1990,!55,!49/57.!
(116)! Leen,!V.;!Yuan,!P.;!Wang,!L.;!Boens,!N.;!Dehaen,!W.!Synthesis!of!Meso/Halogenated!
BODIPYs!and!Access!to!Meso/Substituted!Analogues.!Org.$Lett.$2012,!14,!6150/6153.!
(117)! Nepomnyashchii,!A.!B.;!Bard,!A.!J.!Electrochemistry!and!Electrogenerated!
Chemiluminescence!of!BODIPY!Dyes.!Acc.$Chem.$Res.$2012,!45,!1844/1853.!
(118)! Molander,!G.!A.;!Harris,!C.!R.,!Samarium(II)!Iodide.!In!Encyclopedia$of$Reagents$for$
Organic$Synthesis,!John!Wiley!&!Sons,!Ltd:!2001.!
(119)! Chen,!Y.;!Zhao,!J.;!Guo,!H.;!Xie,!L.!Geometry!Relaxation/Induced!Large!Stokes!Shift!in!
Red/Emitting!Borondipyrromethenes!(BODIPY)!and!Applications!in!Fluorescent!
Thiol!Probes.!J.$Org.$Chem.$2012,!77,!2192/2206.!
(120)! Hafuka,!A.;!Kando,!R.;!Ohya,!K.;!Yamada,!K.;!Okabe,!S.;!Satoh,!H.!Substituent!Effects!at!
the!5/Position!of!3/[Bis(pyridine/2/ylmethyl)amino]/BODIPY!Cation!Sensor!Used!for!
Ratiometric!Quantification!of!Cu²⁺.!Bull.$Chem.$Soc.$Jpn.$2015,!88,!447/
454.!
(121)! Jiao,!L.;!Pang,!W.;!Zhou,!J.;!Wei,!Y.;!Mu,!X.;!Bai,!G.;!Hao,!E.!Regioselective!Stepwise!
Bromination!of!Boron!Dipyrromethene!(BODIPY)!Dyes.!J.$Org.$Chem.$2011,!76,!
9988/9996.!
! 120!
(122)! Peña/Cabrera,!E.;!Aguilar/Aguilar,!A.;!González/Domínguez,!M.;!Lager,!E.;!Zamudio/
Vázquez,!R.;!Godoy/Vargas,!J.;!Villanueva/García,!F.!Simple,!General,!and!Efficient!
Synthesis!of!Meso/Substituted!Borondipyrromethenes!from!a!Single!Platform.!Org.$
Lett.$2007,!9,!3985/3988.!
(123)! Zhao,!N.;!Xuan,!S.;!Fronczek,!F.!R.;!Smith,!K.!M.;!Vicente,!M.!G.!H.!Stepwise!
Polychlorination!of!8/Chloro/BODIPY!and!Regioselective!Functionalization!of!
2,3,5,6,8/Pentachloro/BODIPY.!J.$Org.$Chem.$2015,!80,!8377/8383.!
(124)! Huynh,!A.!M.;!Menges,!J.;!Vester,!M.;!Dier,!T.;!Huch,!V.;!Volmer,!D.!A.;!Jung,!G.!
Monofluorination!and!Trifluoromethylation!of!BODIPY!Dyes!for!Prolonged!Single/
Molecule!Detection.!ChemPhysChem$2016,!17,!433/442.!
(125)! Sekiya,!M.;!Umezawa,!K.;!Sato,!A.;!Citterio,!D.;!Suzuki,!K.!A!novel!luciferin/based!
bright!chemiluminescent!probe!for!the!detection!of!reactive!oxygen!species.!Chem.$
Commun.$2009,!3047/3049.!
(126)! Sugimoto,!H.;!Muto,!M.;!Tanaka,!T.;!Osuka,!A.!Synthesis!of!BODIPY/Appended!
Subporphyrins.!Eur.$J.$Org.$Chem.$2011,!2011,!71/77.!
(127)! Zhai,!J.;!Pan,!T.;!Zhu,!J.;!Xu,!Y.;!Chen,!J.;!Xie,!Y.;!Qin,!Y.!Boronic!Acid!Functionalized!
Boron!Dipyrromethene!Fluorescent!Probes:!Preparation,!Characterization,!and!
Saccharides!Sensing!Applications.!Anal.$Chem.$2012,!84,!10214/10220.!
(128)! Duong,!H.!A.;!Chua,!S.;!Huleatt,!P.!B.;!Chai,!C.!L.!L.!Synthesis!of!Biindolyls!via!
Palladium/Catalyzed!Reactions.!J.$Org.$Chem.$2008,!73,!9177/9180.!
(129)! Ishiyama,!T.;!Murata,!M.;!Miyaura,!N.!Palladium(0)/Catalyzed!Cross/Coupling!
Reaction!of!Alkoxydiboron!with!Haloarenes:!A!Direct!Procedure!for!Arylboronic!
Esters.!J.$Org.$Chem.$1995,!60,!7508/7510.!
(130)! Leen,!V.;!Miscoria,!D.;!Yin,!S.;!Filarowski,!A.;!Molisho!Ngongo,!J.;!Van!der!Auweraer,!
M.;!Boens,!N.;!Dehaen,!W.!1,7/Disubstituted!Boron!Dipyrromethene!(BODIPY)!Dyes:!
Synthesis!and!Spectroscopic!Properties.!J.$Org.$Chem.$2011,!76,!8168/8176.!
!
!

Abstract (if available)

Abstract Solar energy contains a substantial amount of available energy to supply mankind’s demand for power and innovation. Of the emerging technologies, organic photovoltaics (OPVs) are promising cost-effective and light-weight alternatives over traditional silicon solar cells. The organic absorbers used in OPVs are small molecular dyes that are favored for their high absorptivity, well-defined molecular structure, and synthetic versatility. ❧ Boron dipyrrins, or BODIPY, dyes are a class of highly absorbing materials commonly used for biological imaging and fluorescence tagging, but underutilized in the field of OPVs. Recent works have shown them as promising candidates for improving power conversion efficiency and understanding fundamentals of OPVs. By tuning the chemical structure, it is possible to modify the optical and electronic properties of the BODIPY to perform different roles in an OPV device. ❧ A series of BODIPY were synthesized to improve their absorption profile in the red and near-infrared region (Chapter 2 & 5). This allows the donor material to complement the commonly used electron acceptor, C60, covering a larger portion of the solar spectrum (Chapter 3). Electron-withdrawing groups were added to a BODIPY core to enable its function as an electron acceptor. The resulting dye was used as a C60 sensitization, and indicated efficient energy transfer and broadened spectral coverage (Chapter 4). Finally, synthetic studies were examined to investigate the synthetic accessibility of BODIPY dimers (Chapter 6). These molecules exhibit interesting symmetry breaking behavior that can be applied to improving OPV performance.

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Asset Metadata

Creator Chen, John Jun-An (author)

Core Title Properties and applications of dipyrrin-based molecules in organic photovoltaics

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Chemistry

Publication Date 02/10/2017

Defense Date 12/15/2016

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag BODIPY,dye synthesis,OAI-PMH Harvest,organic electronics,organic photovoltaics,solar cells

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Thompson, Mark E. (committee chair), Gupta, Sandeep (committee member), Melot, Brent C. (committee member)

Creator Email chenjj@usc.edu,pandawinner@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c40-333126

Unique identifier UC11257748

Identifier etd-ChenJohnJu-5034.pdf (filename),usctheses-c40-333126 (legacy record id)

Legacy Identifier etd-ChenJohnJu-5034.pdf

Dmrecord 333126

Document Type Dissertation

Rights Chen, John Jun-An

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA