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Front. Chem. | doi: 10.3389/fchem.2019.00016

Development of Red Exciplex for Efficient OLEDs by Employing a Phosphor as a Component

Ming Zhang1,  Kai Wang2,  Cai-Jun Zheng1*, De-Qi Wang1, Yi-Zhong Shi2, Hui Lin1,  Silu Tao1, Xing Li2 and Xiao-Hong Zhang2
  • 1University of Electronic Science and Technology of China, China
  • 2Soochow University, China

Exciplexes are one of the ideal candidates as the effective thermally activated delayed fluorescence (TADF) emitters. However, seldom efficient orange and red TADF exciplexes have been reported, because their significant non-radiative (NR) decays of excited states lead to unavoidable energy loss. Herein, we propose a novel strategy to construct efficient red TADF exciplexes by introducing a phosphor as one component. Due to the strong spin−orbit coupling of heavy metal (e.g., Ir, Pt, et al) ion cores, the NR decays will be evidently decreased for both singlet and triplet excitons, reducing the undesired exciton waste. Moreover, compared with the conventional exciplexes, phosphorescence plays an important role for such novel exciplexes, further improving the exciton utilization. Based on this strategy, we fabricate a red exciplex containing 1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl)tris(diphenylphosphine oxide) (PO-T2T) and tris(2-phenylpyridine) iridium(III) (Ir(ppy)3) as components and realize a red emission with a peak at 604 nm, a CIE coordinate of (0.55, 0.44), and a high maximum external quantum efficiency of 5% in organic light-emitting device. This efficiency is 2.6 times higher than that of the device based on the conventional red exciplex emitter, proving the superiority of our novel strategy to construct red TADF exciplexes with phosphors.

Keywords: exciplex, Thermally activated delayed fluorescence, Phosphor, spin−orbit coupling, Non-radiative decay

Received: 07 Nov 2018; Accepted: 08 Jan 2019.

Edited by:

Lian Duan, Tsinghua University, China

Reviewed by:

Qisheng Zhang, Zhejiang University, China
Toshinori Matsushima, Kyushu University, Japan  

Copyright: © 2019 Zhang, Wang, Zheng, Wang, Shi, Lin, Tao, Li and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Cai-Jun Zheng, University of Electronic Science and Technology of China, Chengdu, 610054, Sichuan Province, China, zhengcaijun@uestc.edu.cn