Spatial & Temporal Dual-Resolved Anti-Counterfeiting Applications in a Long Afterglow System Based on Bismuth Halides

While anticounterfeiting systems based on long persistent luminescence (LPL) materials demonstrate a mature trend, the integration of tunable luminescent lifetimes and emission colors in LPL-based anticounterfeiting systems remains a challenge. Herein, we propose a temporal and spatial anticounterfeiting strategy utilizing novel zero dimensional (0D) metal halides, specifically (PBA)₃BiCl₆:<i>x</i>Sb³⁺ (PBA = 4-Phenylbenzylamine, <i>x</i> = 0, 0.05, 0.1, 0.15), which exhibit long persistent luminescence characteristics. A controllable emission color transition can be observed from green to white to orange by varying the excitation wavelength, accompanied by different afterglow durations of the LPL emission. Additionally, various emission colors are observed at different delay times. Furthermore, the controlled LPL duration is achieved through Sb³⁺ doping in (PBA)₃BiCl₆, attributed to the triplet energy transfer (TET) process. A noticeable afterglow luminescence is observed when using a mobile phone's flashlight as the excitation source, enhancing the portability of the light source. The multifaceted tuning of emission colors and the modulation of the duration of tunable LPL establish a foundation for multicolor and time-resolved anticounterfeiting, significantly elevating the security level of advanced portable anticounterfeiting systems.