Dynamic Fluorescence and Multi-Modal Anti-Counterfeiting Applications in Pb, Mn Co-Doped CsCdCl Perovskite.

Single-component multimodal luminescent materials, particularly those exhibiting dynamic fluorescence properties, have garnered significant attention in the field of high-end information encryption. However, achieving single-component multimodal luminescence, including dynamic fluorescence, in halide perovskites remains a challenge. In this study, a Pb/Mn co-doping strategy is proposed to achieve multiple optical responses in CsCdCl perovskites, including crystal coloration, dynamic fluorescence switching, thermochromism, and long afterglow. Under dark-field conditions, continuous UV irradiation can reversibly switch the fluorescence from orange to blue via an intermediate trap-mediated energy transfer pathway, with the transition time tunable by adjusting the irradiation power. Under bright-field conditions, the degree of crystal coloration can be effectively controlled by tuning the Pb/Mn doping ratio, and the coloration can be rapidly erased through heating or white-light illumination, enabling dual-mode encoding in both bright and dark fields. Furthermore, a time-dependent dynamic fluorescence encoding strategy is developed, and encryption schemes with different decoding approaches are explored. This work presents a novel design strategy for high-security encryption materials featuring multimodal optical responses and dual-mode information storage in both bright and dark fields.