Tetrabenzo[a,c]phenazine Backbone for Highly Efficient Orange–Red Thermally Activated Delayed Fluorescence with Completely Horizontal Molecular Orientation

Umamahesh Balijapalli, Yi Ting Lee, Buddhika S.B. Karunathilaka, Ganbaatar Tumen-Ulzii, Morgan Auffray, Youichi Tsuchiya, Hajime Nakanotani, Chihaya Adachi

Research output: Contribution to journalArticlepeer-review

Abstract

Three thermally activated delayed fluorescence (TADF) molecules, namely PQ1, PQ2, and PQ3, are composed of electron-accepting (A) tetrabenzo[a,c]phenazine (TBPZ) and electron-donating (D) phenoxazine (PXZ) units are designed and characterized. The combined effects of planar acceptor manipulation and high steric hindrance between D and A units endow high molecular rigidity that suppresses nonradiative decay of the excitons with improved photoluminescence quantum yields (PLQYs). Particularly, the well-aligned excited states involving a singlet and a triplet charge-transfer excited states and a localized excited triplet state in PQ3 enhances the reverse intersystem crossing rate constant (kRISC) with a short delay lifetime (τd). The orange–red OLED based on PQ3 displays a maximum external EL quantum efficiency (EQE) of 27.4 % with a well-suppressed EL efficiency roll-off owing to a completely horizontal orientation of the transition dipole moment in the film state.

Original languageEnglish
Pages (from-to)19364-19373
Number of pages10
JournalAngewandte Chemie - International Edition
Volume60
Issue number35
DOIs
Publication statusPublished - Aug 23 2021

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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