Characterizing the Conformational Distribution in an Amorphous Film of an Organic Emitter and Its Application in a “Self-Doping” Organic Light-Emitting Diode

Yi Zhong Shi, Kai Wang, Shao Li Zhang, Xiao Chun Fan, Yoichi Tsuchiya, Yi Ting Lee, Gao Le Dai, Jia Xiong Chen, Cai Jun Zheng, Shi Yun Xiong, Xue Mei Ou, Jia Yu, Jian Sheng Jie, Chun Sing Lee, Chihaya Adachi, Xiao Hong Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

The conformational distribution and mutual interconversion of thermally activated delayed fluorescence (TADF) emitters significantly affect the exciton utilization. However, their influence on the photophysics in amorphous film states is still not known due to the lack of a suitable quantitative analysis method. Herein, we used temperature-dependent time-resolved photoluminescence spectroscopy to quantitatively measure the relative populations of the conformations of a TADF emitter for the first time. We further propose a new concept of “self-doping” for realizing high-efficiency nondoped OLEDs. Interestingly, this “compositionally” pure film actually behaves as a film with a dopant (quasi-equatorial form) in a matrix (quasi-axial form). The concentration-induced quenching that may occur at high concentrations is thus expected to be effectively relieved. The “self-doping” OLED prepared with the newly developed TADF emitter TP2P-PXZ as a neat emitting layer realizes a high maximum external quantum efficiency of 25.4 % and neglectable efficiency roll-off.

Original languageEnglish
JournalAngewandte Chemie - International Edition
DOIs
Publication statusAccepted/In press - 2021

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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