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Highly Efficient Orange‐Red Thermally Activated Delayed Fluorescence Compounds Comprising Dual Dicyano‐Substituted Pyrazine/Quinoxaline Acceptors
Author(s) -
Li Hejun,
Yang Tong,
Wang Jiaxuan,
Xie Ning,
Wang Qingyang,
Xu Yincai,
Zhao Yuguang,
Liang Baoyan
Publication year - 2021
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.202000703
Subject(s) - quinoxaline , chemistry , pyrazine , photochemistry , excited state , acceptor , fluorescence , conjugated system , photoluminescence , stereochemistry , organic chemistry , optoelectronics , polymer , materials science , physics , quantum mechanics , nuclear physics , condensed matter physics
The π‐conjugation of molecules has a large influence on their excited state properties, especially for red thermally activated delayed fluorescence (TADF) materials. Two orange‐red TADF compounds comprising dual dicyano‐substituted pyrazine/quinoxaline acceptors have been designed and synthesized. TPA‐2DCNQ (3,3′‐((phenylazanediyl)bis(4,1‐phenylene))bis(2‐phenylquinoxaline‐6,7‐dicarbonitrile) with extended π‐conjugated quinoxaline as the acceptor exhibits higher photoluminescence quantum yields (ca. 0.67–0.71) in doped films. A smaller energy splitting (ΔE st ) between the first singlet excited state and triplet excited state is also achieved, indicating that extending the π‐conjugation of the acceptor rationally is an effective approach to designing highly efficient long‐wavelength TADF materials. Devices with TPA‐2DCNQ as the emitter display maximum external quantum efficiencies (EQEs) of 12.6–14.0 %, which are more than twice those of devices containing TPA‐2DCNPZ (6,6′‐((phenylazanediyl)bis(4,1‐phenylene))bis(5‐phenylpyrazine‐2,3‐dicarbonitrile).