Asymmetric strategy based on 5-benzofuro[3,2-]carbazole enables efficient narrowband multi-resonance thermally activated delayed fluorescence emitters

Herein, 5 H -benzofuro[3,2- c ]carbazole (BFCz) was introduced into a multi-resonance skeleton to develop two asymmetric emitters, BFCz-B-Cz and BFCz-B-O , which exhibit narrowband green and blue emissions and enhanced reverse intersystem crossing rates. The corresponding pure green and blue OLEDs exhibit high external quantum efficiencies of 26.0% and 11.0%, respectively. Two asymmetric MR-TADF emitters have been developed, which show narrowband green and blue emissions and enhanced reverse intersystem crossing rates.