Luminescence properties and mechanism studies of thermally activated delayed fluorescence molecules

Thermally activated delayed fluorescence (TADF) has gained significant attention as a key mechanism in developing highly efficient organic light-emitting diodes (OLEDs). This review consolidates recent advancements in the theoretical exploration of TADF mechanisms, emphasizing the intricate donor-acceptor (D-A) interactions, the influence of various donor groups on the optical properties, and the behavior of luminescence across different phases. Employing a multiscale simulation, which encompasses density functional theory (DFT) and time- dependent DFT (TD-DFT), this paper elucidates the electroluminescence mechanisms of TADF molecules in both amorphous and crystalline states. The study highlights the significant impact of solid-state interactions on the luminescent properties of TADF materials, offering a comprehensive understanding of the structure-property relationships. These theoretical insights provide a robust foundation for designing next-generation TADF materials with optimized performance, addressing the existing challenges in achieving efficient blue and red light emitters for practical applications in OLED technology. Through this review, we aim to present a coherent overview of the current state of TADF research, identify the critical factors influencing luminescence, and propose strategic directions for future research to further enhance the efficacy and applicability of TADF-based OLEDs.