Modulating Non‐Radiative Deactivation via Acceptor Reconstruction to Expand High‐Efficient Red Thermally Activated Delayed Fluorescent Emitters

Abstract The development of high‐efficient red thermally activated delayed fluorescent (TADF) materials is crucial to expanding their applications. Here, the acceptor reconstruction strategies of acceptor bonding and acceptor fusing in donor–acceptor‐type materials to modulate their nonradiative deactivation process and emission color for expanding high‐efficient red TADF emitters are presented. They are applied to design novel red TADF emitters TXO‐b‐TPA and TXO‐f‐TPA based on non‐red thioxanthone oxide (TXO) acceptor. Compared to TXO‐based emitter TXO‐TPA, these acceptor reconstruction strategies enable red‐shifted (48–88 nm) and efficient red TADF emission (600–640 nm). Their radiative and nonradiative transition processes can be modulated by the different molecular orbital and excited state distributions based on their acceptor structural differences, which results in a dramatic enhancement of their organic light‐emitting diode (OLED) device efficiencies from 1.21/3.63% (TXO‐f‐TPA) to 20.9% (TXO‐b‐TPA). These results confirm that the acceptor reconstruction strategies provide a viable solution for overcoming the limitations of previous red TADF emitters. Moreover, the retrieval of reported TADF materials can further demonstrate that these acceptor reconstruction strategies can be transferrable to more non‐red TADF materials to expand high‐efficient red‐shift and/or red TADF materials.