Host-guest doping strategy for achieving ultralong multicolor room-temperature phosphorescence in benzophenone-aromatic compounds.

Organic room-temperature phosphorescent materials, owing to their advantages such as large Stokes shifts and long-lived delayed emission, have significant potential for applications in areas such as luminescent displays and information encryption. Currently, host-guest doping remains the mainstream strategy for achieving room-temperature phosphorescence; however, issues such as complex preparation methods and limited emission color range still need to be addressed. In this work, a simple one-step in situ molten host-guest doping strategy is employed to embed polycyclic aromatic hydrocarbon derivatives into a benzophenone matrix. The rigid microenvironment formed upon cooling and crystallization effectively suppresses the non-radiative decay of guest molecules. Additionally, through the modulation of the conjugated structure and substituents of the guest molecules, a controllable tuning of the emission color ranging from cyan to red is achieved. Notably, the composite material PC3A/BPO exhibits a red ultralong afterglow with a lifetime of 231 ms upon 365 nm excitation. Theoretical calculations clearly reveal the intermolecular charge transfer (CT) process within the host-guest system, which lowers the excitation state energy level and enhances spin-orbit coupling, thereby enabling stable and efficient RTP emission. Finally, the obtained host-guest composite materials are successfully applied in multi-level anti-counterfeiting encryption, demonstrating their potential for applications in information security.