Managing Locally Excited and Charge-Transfer Triplet States to Facilitate Up-Conversion in Red TADF Emitters That Are Available for Both Vacuum- and Solution-Processes

Jia-Xiong Chen, Ya-Fang Xiao, Kai Wang*, Dianming Sun, Xiao-Chun Fan, Xiang Zhang, Ming Zhang, Yi-Zhong Shi, Jia Yu, Feng-Xia Geng, Chun-Sing Lee*, Xiao-Hong Zhang*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

150 Citations (Scopus)

Abstract

Developing red thermally activated delayed fluorescence (TADF) emitters for high-performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ-DPXZ, pDTBPZ-DPXZ, and oDTBPZ-DPXZ, are designed and synthesized with same donor–acceptor (D-A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ-DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum-processed OLED, but also realize a high EQE of 18.5 % in a solution-processed OLED, which is among the best results in solution-processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up-conversion process and thus enhance exciton harvesting.
Original languageEnglish
Pages (from-to)2478-2484
JournalAngewandte Chemie - International Edition
Volume60
Issue number5
Online published20 Oct 2020
DOIs
Publication statusPublished - 1 Feb 2021

Research Keywords

  • charge-transfer triplet state
  • locally excited triplet state
  • solution-processed OLED
  • thermally activated delayed fluorescence
  • vacuum-deposited OLED

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