Improved electrophosphorescence efficiency for organic light-emitting diodes using the cohost with stepwise blending profile

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• 作者：Jianzhuo Zhu ; Wenlian Li ; Bei Chu ; Dongfang Yang ; Guang Zhang ; Fei Yan ; Huihui Liu ; Junbo Wang ; Shuanghong Wu
• 关键词：Improved efficiency ; Cohost ; Stepwise blending
• 刊名：Displays
• 出版年：2010
• 出版时间：July 2010
• 年：2010
• 卷：31
• 期：3
• 页码：128-131
• 全文大小：423 K

文摘

A tris(2-phenylpyridine) iridium doped phosphorescent organic light-emitting diode using a mixed host with stepwise blending profile was demonstrated. We adopted the mixture of 4,4′,4″-tris(N-carbazolyl) triphenylamine and 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene as the host in the emitting layer. By using a stepwise blending ratio profile of the two host materials, a peak external quantum efficiency of 17.7 % and a peak power efficiency of 45.7 lm/W were attained, which increased by 59.5 % and 60.9 % relative to the optimal uniform blending ratio profile based device, respectively. The efficiency improvement was attributed to the multiple exciton formation interfaces, which could expand the recombination regions.