Engineered Energy Transfer in Room Temperature Phosphorescent Materials for Time‐Resolved Dual‐Mode Encryption

Abstract Room temperature phosphorescence (RTP) materials are of significant attentions due to their unique optical properties and potential applications in anti‐counterfeiting and information security. However, single spatial resolution anti‐counterfeiting decryption methods fail to meet high‐level security demands. A novel dual‐mode information encryption strategy based on self‐trapped exciton (STE) fluorescence and phosphorescence is proposed. By introducing ns² metal ions into the zero‐dimensional organic–inorganic hybrid metal halide (Ph₃S)₂SnCl₆, energy transfer pathways from the S₁ and T_n energy levels to the STEs are constructed, enabling precise control of phosphorescence performance. This material exhibited STE fluorescence‐phosphorescence dual‐mode optical properties with different afterglow time, which can be utilized to develop high‐performance time‐resolved cryptographic systems. Femtosecond transient absorption experiments indicated that the energy transfer rate from the S₁ to STEs significantly affected the time‐resolved characteristics of long afterglow materials. The potential of this material in time‐resolved cryptographic systems is demonstrated, enhancing security through time‐resolved multi‐level encryption and providing a new avenue for advanced anti‐counterfeiting and information security.