Modulation for efficiency and spectra of non-doped white organic light emitting diodes by combining an exciplex with an ultrathin phosphorescent emitter

Zemei Liu; Bo Zhao; Yuan Gao; Haifeng Chen; Bizheng Dong; Yabo Xu; Hua Wang; Bingshe Xu; Wenlian Li

doi:10.1039/d0ra06658c

Modulation for efficiency and spectra of non-doped white organic light emitting diodes by combining an exciplex with an ultrathin phosphorescent emitter

RSC Adv. 2020 Sep 10;10(55):33461-33468. doi: 10.1039/d0ra06658c. eCollection 2020 Sep 7.

Authors

Zemei Liu¹, Bo Zhao¹, Yuan Gao², Haifeng Chen³, Bizheng Dong¹, Yabo Xu¹, Hua Wang¹, Bingshe Xu¹, Wenlian Li⁴

Affiliations

¹ Key Laboratory of Interface Science and Engineering in Advanced Materials of Ministry of Education, Taiyuan University of Technology Taiyuan 030024 China zhaobo01@tyut.edu.cn wanghua001@tyut.edu.cn.
² College of Economics and Management, Chongqing University of Arts and Sciences Chongqing 402160 China yuangao@cqwu.edu.cn.
³ School of Electronic Information and Electrical Engineering, Chongqing University of Arts and Sciences Chongqing 402160 China.
⁴ State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun 130033 China.

Abstract

Herein, structured non-doped white organic light-emitting diodes (WOLEDs) were designed by combining the emission of a blue exciplex and orange-red phosphorescent ultrathin layer. The device efficiency and spectra were modulated successfully by adjusting the thickness of the exciplex layer and ultrathin layer, respectively. Meanwhile, high efficiency with external quantum efficiency (EQE) ranging from 15% to 22%, power efficiency from 33 lm W^-1 to 47 lm W^-1 and warm white emission with correlated color temperature (CCT) from 1600 K to 2600 K were realized. The energy transfer process and emission mechanism is also discussed, and the results reveal that the efficient charge trapping and recombination contribute to the improvement of device efficiency and reduce the roll-off efficiency.