Organic light-emitting diodes (OLEDs) have attracted much attention in recent years. Among organic electroluminescent materials, thermally activated delayed fluorescent (TADF) materials, which could harvest both singlet and triplet excitons to afford internal quantumn efficiencies of 100%, are emerging as one of the third-generation organic electroluminescent materials. However, TADF materials have to suffer from aggregation-caused quenching (ACQ) effect, which results in reduced luminance efficiencies. Aggregation-induced emission (AIE) materials have excellent emission efficiencies by suppressing concentration quenching. Therefore, a few of TADF materials with AIE characters have been reported. In this review, the research progress of OLED materials, the related mechanisms of TADF, TTA, HLCT and AIE, the design principles of TADF materials are briefly introduced. The paper specially focuses on the outputs of works on the photophysical performance improvement of TADF materials with AIE effect and relevant devices, in which carbonyl, diphenyl sulfone, triazine and other representative electron withdrawing groups are utilized as electron acceptors. In design concept of TADF materials with benzophenone substituents, asymmetric structures are adopted to construct TADF materials, which can enhance AIE characteristics of the molecules, and also reduce ΔEST values due to increased rigidity of the molecular. Compared with phenylsulfone groups considered as acceptors for TADF materials can form a larger torsion angle, which is more inclined to form AIE properties. Moreover, triazine units in TADF materials provide multiple grafting points for the combination with electron donors, and consequently, facilitate the adjustment of intramolecular deflection angle and energy level. The paper ends with a prospective discussion on the future trend of TADF materials with AIE properties, which is expected to provide a meaningful theoretical guidance for the design this type of novel materials. © 2020, Materials Review Magazine. All right reserved.
