Improved efficiency roll-off at high brightness in simplified phosphorescent organic light emitting diodes with a crossfading-host |
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| Authors: | Jing Wang Jun Liu Saijun Huang Xinkai Wu Xindong Shi Gufeng He Youxuan Zheng |
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| Affiliation: | 1. National Engineering Lab for TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China;2. State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China |
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| Abstract: | We report a high efficiency and low efficiency roll-off green phosphorescent organic light emitting diode using both hole- and electron-transporting host materials in a crossfading profile. To eliminate the energy barrier and reduce the charge carrier accumulation, the host materials are used as transporting layers as well, which also simplifies the device fabrication. It is found out that the recombination zone of gradient doping host sample is not only wider but also extended at high current density, which contributes to the suppressed efficiency roll-off at high luminance. An external quantum efficiency of 21.0% at 1000 cd/m2 is obtained, and maintains to 19.3% at 10,000 cd/m2. |
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| Keywords: | Phosphorescent organic light emitting High efficiency Low roll-off Crossfading-host |
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