High efficiency yellow organic light-emitting diodes with a solution-processed molecular host-based emissive layer

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 1; no. 8; pp. 1680 - 1686
• Main Authors: Jou, Jwo-Huei, Peng, Shiang-Hau, Chiang, Cheng-I., Chen, Yu-Lin, Lin, You-Xing, Jou, Yung-Cheng, Chen, Cheng-Hua, Li, Chieh-Ju, Wang, Wei-Ben, Shen, Shih-Ming, Chen, Sun-Zen, Wei, Mao-Kuo, Sun, Young-Shan, Hung, Hsiao-Wen, Liu, Ming-Chung, Lin, Yi-Ping, Li, Jung-Yu, Wang, Ching-Wu
• Format: Journal Article
• Language: English
• Published: 01.01.2013
• Subjects: Devices; Emissivity; Emitters (electron); Energy transfer; Excitons; Organic light emitting diodes
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c2tc00249c

Highly efficient yellow organic light-emitting diodes (OLEDs) with a solution-process feasible emissive layer were fabricated by simply using molecular hosts doped with an iridium-complex based yellow emitter. The best yellow OLED device studied here showed for example, at 100 cd m super(-2), a power efficiency of 32 lm W super(-1), a 113% improvement compared with the prior record of 15 lm W super(-1) based on the same emitter with a polymeric host. The marked efficiency improvement may be attributed to the device being composed of an electron-injection-barrier free architecture, a device structure that led the excitons to generate preferably on the host to enable the efficiency-effective host-to-guest energy transfer to occur and the employed molecular host that exhibited a good host-to-guest energy transfer. The efficiencies were further improved to 53, 39 and 14 lm W super(-1) at 100, 1000 and 10 000 cd m super(-2), respectively, with the use of a micro-lens. This study also demonstrates the possibility of achieving relatively high device efficiency for wet-processed OLED devices viabalancing the injection of carriers with commercially available OLED materials and limited designs in device structure.