A Strategy for Designing Multifunctional TADF Materials for High‐Performance Non‐doped OLEDs by Intramolecular Halogen Bonding

Abstract The development of multifunctional thermally activated delayed fluorescence (TADF) material with high efficiency is indeed a formidable challenge. The difficulty arises from the need to achieve multiple desirable radiation pathways simultaneously during the emission process. In this context, a novel strategy to construct multifunctional emitters with high emission efficiency by modulating intramolecular halogen bonding through structural isomerism is proposed. The designed molecule DMAC‐2FDPS exhibits multifunctional features, including aggregation‐induced emission, mechanochromic luminescence, room temperature phosphorescence, mechanoluminescence, and TADF. Notably, in neat film, DMAC‐2FDPS demonstrates an exceptionally high photoluminescence quantum efficiency of up to 93%. Through single‐crystal analysis and theoretical calculations, it is revealed that the intramolecular halogen bonding in this molecule plays a crucial role in achieving both multifunctional emission and high PLQY. Furthermore, when utilized in non‐doped organic light‐emitting diodes (OLEDs), DMAC‐2FDPS achieves a maximum external quantum efficiency of up to 21.2%. To the best acknowledge, it is almost the highest efficiency for non‐doped OLEDs based on multifunctional materials with five characteristics. These results certify a new strategy for the development of high‐efficiency multifunctional TADF materials and devices.