Document Type

Journal Article

Department/Unit

Department of Chemistry

Title

Robust Tris-Cyclometalated Iridium(III) Phosphors with Ligands for Effective Charge Carrier Injection/Transport: Synthesis, Redox, Photophysical, and Electrophosphorescent Behavior

Language

English

Abstract

With the target to design and develop new functionalized green triplet light emitters that possess distinctive electronic properties for robust and highly efficient phosphorescent organic light-emitting diodes (PHOLEDs), a series of bluish-green to yellow-green phosphorescent tris-cyclometalated homoleptic iridium(III) complexes [Ir(ppy-X)3] (X = SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO 2Ph, Hppy = 2-phenylpyridine) have been synthesized and fully characterized by spectroscopic, redox, and photophysical methods. By chemically manipulating the lowest triplet-state character of Ir(ppy)3 with some functional main-group 14-16 moieties on the phenyl ring of ppy, a new family of metallophosphors with high-emission quantum yields, short triplet-state lifetimes, and good hole-injection/holetransporting or electron-injection/ electron-transporting properties can be obtained. Remarkably, all of these IrIII complexes show outstanding electrophosphorescent performance in multilayer doped devices that surpass that of the state-of-the-art green-emitting dopant Ir(ppy)3. The devices described herein can reach the maximum external quantum efficiency (ηext) of 12.3%, luminance efficiency (ηL) of 50.8 cdA-1, power efficiency (ηp) of 36.9 LmW-1 for [Ir(ppy-SiPh 3)3], 13.9%, 60.8 cdA-1, 49.1 LmW-1 for [Ir(ppy-NPh2)3], and 10.1%, 37.6 cdA-1, 26.1 Lm W-1 for [Ir(ppy-SO2Ph)3]. These results provide a completely new and effective strategy for carrier injection into the electrophosphor to afford high-performance PHOLEDs suitable for various display applications. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.

Keywords

Electron transport, Iridium, Main group elements, Phosphorescence, UV/Vis spectroscopy

Publication Date

2008

Source Publication Title

Chemistry - An Asian Journal

Volume

3

Issue

10

Start Page

1830

End Page

1841

Publisher

Wiley-VCH Verlag

DOI

10.1002/asia.200800074

Link to Publisher's Edition

http://dx.doi.org/10.1002/asia.200800074

ISSN (print)

18614728

ISSN (electronic)

1861471X

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