Cyclometalated Ir(III) Complexes for High-Efficiency Solution-Processable Blue PhOLEDs

Valery Kozhevnikov, Yonghao Zheng, Matthew Clough, Hameed Al-Attar, Gareth Griffiths, Khalid Abdullah, Steponas Raisys, Vygintas Jankus, Martin Bryce, Andrew Monkman

Research output: Contribution to journalArticlepeer-review

99 Citations (Scopus)

Abstract

This article reports the systematic functionalization of FIrpic (1) with solubilizing alkyl groups (complexes 2–4) or mesityl groups (complexes 5 and 6). Complex 5 is shown to offer significant advantages over FIrpic (1) in terms of performance of sky-blue polymer-based phosphorescent organic light-emitting diodes (PhOLEDs) with a solution-processed emitting layer (λmaxEL 477 nm for 5). Devices with 5 doped into poly(vinylcarbazole) (PVK):OXD-7 gave a maximum luminous efficiency of 19.1 cd A–1 at a brightness of 5455 cd m2 with EQE 8.7%. Optimized multilayer devices with additional TPBi and LiF layers gave 23.7 cd A–1 and EQE 10.4%. These data compare favorably with leading literature values for sky-blue polymer-based PhOLEDs. The enhanced performance of 5 is ascribed to three main reasons: (i) reduced concentration quenching of 5; (ii) the higher radiative yield of 5; and (iii) improved solubility of 5 in organic solvents. Complex 5 should find widespread use as a soluble blue phosphor for displays and lighting applications using solution processing techniques.
Original languageEnglish
Pages (from-to)2352-2358
JournalChemistry of Materials
Volume25
Issue number11
DOIs
Publication statusPublished - 2013

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