Light driven CsPbI3 perovskite quantum dots core-shell transformation for Snapchat type anti-counterfeiting and encryption in 4D codes

Time based dynamic fluorescence encryption and anti-counterfeiting has seized great attention for advanced information security. However, it remains a great challenge to develop tunable multicolor photoluminescent systems with low cost, facile fabrication, mass processability and convenient authentication. Herein, we have developed a dynamic anti-counterfeiting and encryption strategy based on multicolor emission system resulted by core–shell structure transformation of CsPbI 3 perovskite quantum dots (PQDs). Tunable multicolor emissions, including red, orange, yellow, and green emissions, could be easily achieved by controlling halide exchanges between hexabromocyclododecanes and CsPbI 3 PQDs under 254 nm UV irradiation. Based on this feature, 4D codes time dependent Snapchat-type information encryption system has been successfully developed, showing multiple pieces of information on a time scale, and the correct information can be identified only at a specified time. After excessive ultraviolet irradiation, the color will be unified into green, and the coding information will be erased. This work provides an inspiring point for the design of information encryption materials with higher security requirements.