Diarylboron‐Based Asymmetric Red‐Emitting Ir(III) Complex for Solution‐Processed Phosphorescent Organic Light‐Emitting Diode with External Quantum Efficiency above 28%. Issue 5 (6th March 2018)

• Record Type: Journal Article
• Authors: Yang, Xiaolong; Guo, Haoran; Liu, Boao; Zhao, Jiang; Zhou, Guijiang; Wu, Zhaoxin; Wong, Wai‐Yeung
• Is Part Of: Advanced science. Volume 5:Issue 5(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-06
• Subjects: asymmetric Ir(III) complexes -- diarylboron -- high efficiency diodes -- red phosphor -- solution‐processed organic light‐emitting diodes; Science -- Periodicals; 505
• DOI: 10.1002/advs.201701067
• Languages: English
• ISSNs: 2198-3844

Abstract

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. Abstract : Highly efficient phosphorescent red‐emitting Ir(III) complexes with asymmetric structure are developed. The solution‐processed organic light‐emitting diode (OLED) based on the diarylboron‐based asymmetric Ir(III) complexBPyThIr exhibits peak external quantum efficiency, current efficiency, and power efficiency of 28.5%, 54.4 cd A −1, and 50.1 lm W −1, respectively, with very low efficiency roll‐off. This is one of the best performances ever reported for Ir(III) complex‐based red OLEDs.