Realizing Color-Tunable and Time-Dependent Ultralong Afterglow Emission in Antimony-Doped CsCdCl3 Metal Halide for Advanced Anti-Counterfeiting and Information Encryption

Long afterglow luminescent materials have captured intense attention for their unique applications in biological imaging, photodynamic therapy, and optical anti-counterfeiting. However, achieving highly efficient and tunable ultralong afterglow emission in all-inorganic metal halides is an open challenge. Herein, Sb3+-doped hexagonal CsCdCl3 metal halide is reported via hydrothermal reaction. Upon photoabsorption, the as-synthesized compounds exhibit dual-emission bands with a photoluminescence quantum yield (PLQY) of 59.6%, which can be attributed to the self-trapped exciton emission out of the strong electron-phonon coupling. After ceasing excitation of 365 nm, bright afterglow emission with the longest duration lasting up to 5000 s is witnessed in Sb3+-doped CsCdCl3. More importantly, the color-tunable and time-dependent ultralong afterglow emission is realized via regulating the doping concentration of Sb3+, which should be due to the trap electrons increase gradually under high doping concentration. Given this unusual afterglow emission characteristics, the optical anti-counterfeiting and information encryption are constructed based on as-synthesized compounds. These findings not only help further understand the tunable afterglow emission mechanism in all-inorganic metal halides, but also provide a new strategy for designing novel ultralong afterglow luminescent materials.