Unexpected Room‐Temperature Phosphorescence/Long Persistent Luminescence Dual Changes Induced by Conformational Freezing in Difluoroboron β‐Diketonate Systems

Room-temperature phosphorescence (RTP) and organic long persistent luminescence (OLPL) materials are the current research hotspots in the field of luminescence and have broad application prospects, but afterglow systems with stimulus response or dynamic changes are still rare. Herein, we report unexpected dual afterglow change induced by conformational freezing in difluoroboron β-diketonate (BF₂bdk) systems. The cyclized BF₂bdk system (after conformational freezing) exhibits bright green RTP followed by weak OLPL, whereas noncyclized BF₂bdk system (before conformational freezing) displays blue thermally activated delayed fluorescence (TADF)-type afterglow with subsequent stronger OLPL. In-depth investigations reveal that the inversion in afterglow intensity and mechanism change arise from the difference in ΔE_ST as well as the ability to undergo charge separation and harvest of excitons. Besides, this dual afterglow changing behavior with brightness inversion over time demonstrates significant potential for advanced dynamic anticounterfeiting and multilevel information encryption applications.