Dynamic Fluorescence and Multi‐Modal Anti‐Counterfeiting Applications in Pb ²⁺ , Mn ²⁺ Co‐Doped CsCdCl ₃ Perovskite

Abstract 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 ²⁺ /Mn ²⁺ co‐doping strategy is proposed to achieve multiple optical responses in CsCdCl ₃ 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 ²⁺ /Mn ²⁺ 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.