Highly efficient chlorine functionalized blue iridium( iii ) phosphors for blue and white phosphorescent organic light-emitting diodes with the external quantum efficiency exceeding 20

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 6; no. 25; pp. 6656 - 6665
• Main Authors: Miao, Yanqin, Tao, Peng, Gao, Long, Li, Xiangling, Wei, Liuwei, Liu, Shujuan, Wang, Hua, Xu, Bingshe, Zhao, Qiang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Chlorine; Dichloromethane; Efficiency; Emitters; Iridium; Organic light emitting diodes; Phosphorescence; Phosphors; Quantum efficiency
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C8TC01098F

The absence of highly efficient and stable blue phosphors is still a bottleneck for the development of high quality monochrome and white phosphorescent organic light-emitting diodes (OLEDs). Here, we propose a chlorine-functionalization strategy for blue phosphors, and a series of aromatic chlorine-based high-efficiency blue iridium( iii ) phosphors ( Ir1–Ir4 ) containing various ancillary ligands was designed and prepared. These phosphors show intensive blue emissions withPL peaks of 468–476 nm and a high Φ PL of 0.70–0.85 in dichloromethane. Using these blue phosphors as emitters, the fabricated OLEDs also realize similar blue emissions with the peaks located at 472, 484, 476, and 476 nm for the Ir1–Ir4 -based OLEDs, respectively. Moreover, the Ir2 - and Ir3 -based OLEDs exhibit extremely high EQEs exceeding the theoretical limit, reaching 20.43% and 21.41%, respectively. In addition, the two-color white OLED with Ir3 as the blue emitter also achieves an extremely high device efficiency, having a maximum EQE of up to 20.17%. The excellent blue emission and high device efficiency indicates that the four phosphors have huge potential applications for high performance blue and white phosphorescent OLEDs.