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

Kozhevnikov, Valery N.; Zheng, Yonghao; Clough, Matthew; Al-Attar, Hameed A.; Griffiths, Gareth C.; Abdullah, Khalid; Raisys, Steponas; Jankus, Vygintas; Bryce, Martin R.; Monkman, Andrew P.

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.

Citation

Kozhevnikov, V. N., Zheng, Y., Clough, M., Al-Attar, H. A., Griffiths, G. C., Abdullah, K., …Monkman, A. P. (2013). Cyclometalated Ir(III) Complexes for High-Efficiency Solution-Processable Blue PhOLEDs. Chemistry of Materials, 25(11), 2352-2358. https://doi.org/10.1021/cm4010773

• Journal Article Type: Article
• Publication Date: Jun 11, 2013
• Deposit Date: Nov 24, 2014
• Publicly Available Date: Nov 26, 2014
• Journal: Chemistry of Materials
• Print ISSN: 0897-4756
• Electronic ISSN: 1520-5002
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 25
• Issue: 11
• Pages: 2352-2358
• DOI: https://doi.org/10.1021/cm4010773
• Keywords: Iridium complex, phosphorescence, Electroluminescence, Blue emission, OLED.
• Public URL: https://durham-repository.worktribe.com/output/1419385