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SYNTHESIS AND PHOTOPHYSICAL CHARACTERIZATION OF
PHOSPHORESCENT CYCLOMETALATED IRIDIUM (III) COMPLEXES
AND THEIR USE IN ORGANIC LIGHT EMITTING DEVICES
by
Tissa Sajoto
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)
May 2008
Copyright 2008 Tissa Sajoto
Object Description
| Title | Synthesis and photophysical characterization of phosphorescent cyclometalated iridium (III) complexes and their use in OLEDs |
| Author | Sajoto, Tissa |
| Author email | sajoto@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemistry |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-03-27 |
| Date submitted | 2008 |
| Restricted until | Restricted until 21 Apr. 2010. |
| Date published | 2010-04-21 |
| Advisor (committee chair) | Thompson, Mark E. |
| Advisor (committee member) |
Bau, Robert Prakash, Surya Haw, James Weber, William Goo, Edward |
| Abstract | Organic light emitting devices (OLEDs) are a new type of display technology based on organic thin films. The materials that comprise these films must be able to meet certain criteria in order to be considered for these devices. The work presented here describes the development of novel phosphorescent materials along with their photophysical characterization and applications in OLEDs. Chapter 1 illustrates how these devices work, the materials used in these devices, and how the properties of these materials affect device performance. Chapter 2 describes the synthesis and characterization of high energy phosphorescent materials from Ir(III) complexes with cyclometalated pyrazolyl-based and N-heterocyclic carbene (NHC)-based ligands. Chapter 3 portrays the synthesis and characterization of heteroleptic Ir(III) complexes consisting of two chromophoric cyclometalating (C^N) ligands and a single high energy ancillary ligand (L^X). The incorporation of high energy ancillary ligands such as pmi on bis-cyclometalated Ir(ppz)2 does not lead to emission at room temperature. However, the replacement of the ppz chromophoric ligands with carbazolyl, diphenylamino, or fluorenylpyrazolyl-based chromophoric ligands leads to emission at room temperature. In Chapter 3, more reducible flz-based Ir(III) complexes have also been synthesized by incorporation of a high triplet energy, more reducible ancillary ligand. Their electrochemical, spectroscopic, and electroluminescent properties are discussed.; Chapter 4 discusses the synthesis and photophysics of triscyclometalated Ir(III) benzoquinolinecomplexes, Ir(bzq)3. White phosphorescent OLEDs with mer-Ir(bzq)3 as the broad band emitter have been fabricated with a maximum external quantum efficiency of ~12%. In Chapter 5, we utilize extensive temperature dependent lifetime studies to estimate the zero-field splitting (ZSF) and ligand-field (LF) state energies for blue and near-UV phosphorescent cyclometalated Ir(III) complexes. This is the first time we can identify where the LF state is for blue cyclometalated Ir(III) complexes. The thermal population of the LF state is most likely one of the deactivation processes that blue cyclometalated Ir(III) complexes exhibit. From the temperature dependent study, we learn that the activation energies (Ea) needed to thermally populate LF state and thenonradiative decay rate constant (knr(T)) are important factors that affect the quantum efficiencies of high energy phosphorescent cyclometalated Ir(III) complexes. |
| Keyword | OLEDs; iridium; cyclometalated; phosphorescent |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m1162 |
| Rights | Sajoto, Tissa |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Sajoto-20080421 |
| Archival file | uscthesesreloadpub_Volume26/etd-Sajoto-20080421.pdf |
Description
| Title | Page 1 |
| Full text | SYNTHESIS AND PHOTOPHYSICAL CHARACTERIZATION OF PHOSPHORESCENT CYCLOMETALATED IRIDIUM (III) COMPLEXES AND THEIR USE IN ORGANIC LIGHT EMITTING DEVICES by Tissa Sajoto A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CHEMISTRY) May 2008 Copyright 2008 Tissa Sajoto |
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