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Adv Sci (Weinh). 2018 Mar 6;5(5):1701067. doi: 10.1002/advs.201701067. eCollection 2018 May.

Diarylboron-Based Asymmetric Red-Emitting Ir(III) Complex for Solution-Processed Phosphorescent Organic Light-Emitting Diode with External Quantum Efficiency above 28.

Author information

1
MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Institute of Chemistry for New Energy Material Department of Chemistry School of Science State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 P. R. China.
2
Key Laboratory for Physical Electronics and Devices of the Ministry of Education Faculty of Electronic and Information Engineering Xi'an Jiaotong University Xi'an 710049 P. R. China.
3
Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic University Hung Hom Hong Kong P. R. China.

Abstract

Organic light-emitting diodes (OLEDs) are one of the most promising technologies for future displays and lighting. Compared with the blue and green OLEDs that have achieved very high efficiencies by using phosphorescent Ir(III) complexes, the red OLEDs still show relatively low efficiencies because of the lack of high-performance red-emitting Ir(III) complexes. Here, three highly efficient asymmetric red-emitting Ir(III) complexes with two different cyclometalating ligands made by incorporating only one electron-deficient triarylboron group into the nitrogen heterocyclic ring are reported. These complexes show enhanced photoluminescence quantum yields up to 0.96 and improved electron transporting capacity. In addition, the asymmetric structure can help to improve the solubility of Ir(III) complexes, which is crucial for fabricating OLEDs using the solution method. The photoluminescent and oxidation-reduction properties of these Ir(III) complexes are investigated both experimentally and theoretically. Most importantly, a solution-processed red OLED achieves extremely high external quantum efficiency, current efficiency, and power efficiency with values of 28.5%, 54.4 cd A-1, and 50.1 lm W-1, respectively, with very low efficiency roll-off. Additionally, the related device has a significantly extended operating lifetime compared with the reference device. These results demonstrate that the asymmetric diarylboron-based Ir(III) complexes have great potential for fabricating high-performance red OLEDs.

KEYWORDS:

asymmetric Ir(III) complexes; diarylboron; high efficiency diodes; red phosphor; solution‐processed organic light‐emitting diodes

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