Recent progress in high-performance thermally activated delayed fluorescence exciplexes based on multiple reverse intersystem crossing channels

In the field of organic light-emitting diodes (OLEDs), exciplex materials with thermally activated delayed fluorescence (TADF) characteristics have garnered significant attention in recent years owing to their potential for high fluorescence efficiency, primarily achieved through the reverse intersystem crossing (RISC) process. By converting non-radiative triplet states to radiative singlet states, the RISC process can effectively regulate exciton behavior, resulting in the harvest of triplet excitons and the improvement of luminescence efficiency. Recently, multi-RISC strategies have been developed to further enhance the performance of TADF exciplex materials and devices. In this paper, we review these research progress in this area. We classify molecular design strategies according to the composition of exciplexes, discuss the design principles and energy-harvesting mechanism of high-performance TADF exciplexes based on multi-RISC strategies, and prospect their further research and development. The progressive endeavors summarized in this review may inspire further research on material design and device fabrication, and promote the development of OLED applications.