Twisted Biphenyl-Diimide Derivatives with Aggregation-Induced Emission and Thermally Activated Delayed Fluorescence for High Performance OLEDs

π-Conjugated arylene diimide derivatives as a kind of well-known organic dyes have been widely used as building blocks for constructing n-type semiconductors. However, the large π-framework faded their solid-state emission, which hinders their application in organic light-emitting diodes (OLEDs). Herein, two novel π-conjugated donor–acceptor–donor (D-A-D) type compounds BPI-PhPXZ and BPI-PhDMAC, composed of twisted biphenyl-diimide (BPI) acceptors and phenoxazine or acridine donors are synthesized. BPI-PhPXZ and BPI-PhDMAC show prominent aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF), and enjoy good thermal and electrochemical stabilities. Doped OLEDs fabricated with the two compounds have achieved high external quantum efficiencies (EQEs) of 18.1% and 16.2%, respectively. The results highlight the beneficial role of well-designed BPI acceptor for the development of efficient D-A-D type TADF emitters with AIE properties.