Controlling ISC/RISC Competition Through Triplet State Characteristics Modulation in Pure Organic RTP Emission

To achieve purely organic room-temperature phosphorescence, one common strategy involves introducing n→π* transitions into the molecule to enhance spin-orbit coupling. However, molecules designed with such structures typically require special conditions, such as low temperatures or a rigid environment, to exhibit room-temperature phosphorescent emission. Building on this, further introducing heavy atoms into the molecule can enhance room-temperature phosphorescence performance but often comes with strong fluorescence emission, leading to reduced phosphorescence efficiency. While adopting a donor–acceptor configuration can achieve relatively pure room-temperature phosphorescence emission, the system inherently involves competing processes of inter-system crossing and reverse inter-system crossing, and clear strategies for effectively suppressing reverse inter-system crossing remain elusive. To address this issue, this study systematically investigates the properties of triplet excitons by modulating molecular configurations and reveals a significant correlation between the proportion of triplet localized states and the resulting luminescence characteristics.