Lead-Free\nManganese\nHalide Perovskite for Minute-Level\nDynamic Time-Gating Anticounterfeiting

The dynamic time-gating anticounterfeiting\nbased on phosphorescence\nmaterials is the current hot topic of research. However, the short\nchange time from nanosecond-level fluorescence false information to\nμs-level fluorescence correct information makes it easily deciphered\njust by turning off ultraviolet (UV) light. Herein, we first reported\na new type of minute-level dynamic time-gating anticounterfeiting\ntechnology based on the ethanol-induced phase transition between the\nred-emitting CsMnBr<sub>3</sub> crystals and green-emitting Cs<sub>3</sub>MnBr<sub>5</sub> crystals. Our results show that the dissolution\nof MnBr<sub>2</sub>·2H<sub>2</sub>O from CsMnBr<sub>3</sub> into\nethanol triggers the phase transition. Moreover, the time of phase\ntransition can be adjusted by mixing with different (3-aminopropyl)triethoxysilane\n(APTES) concentrations. By using CsMnBr<sub>3</sub> and APTES-CsMnBr<sub>3</sub> with different phase-transition times, the true information\non “SEO” can be designed to show only in the conditions\nof specific stimulus (ethanol) and specific time range. Otherwise,\nthe false information on “SEU” or “888”\nis shown. In comparison to previously reported dynamic time-gating\nanticounterfeiting technology based on phosphorescence materials,\nthe current reported minute-level dynamic time-gating anticounterfeiting\ntechnology based on phase transition increased the difficulty of decryption.\nMoreover, the combination of nontoxic fluorescence materials and daily\nlife available stimulus (ethanol) makes the current anticounterfeiting\ntechnology have great practical value.