Green and Scalable Sb-Doped Rare-Earth Halide Perovskite Phosphors for Multilevel Optical Information Encryption

Developing environmentally benign luminescent materials with high emission efficiency, recyclability, and dynamically tunable optical properties is crucial for sustainable optical information encryption. However, achieving green synthesis, scalable production, and stimulus-responsive optical tunability simultaneously remains challenging. Herein, Sb-doped rare-earth halide perovskite phosphors are rapidly synthesized via a low-energy aqueous-phase evaporation-crystallization strategy, avoiding organic solvents and corrosive reagents, and enabling gram-scale production. The obtained Cs2NaYCl6:Sb, Cs2KYCl6:Sb, Rb3YCl6:Sb and Rb2ScCl5·H2O:Sb phosphors exhibit multicolor emission from blue to orange with photoluminescence quantum yields (PLQYs) exceeding 80%. They feature three-dimensional or zero-dimensional crystal structures with micrometer-scale irregular morphology, along with excellent long-term UV and thermal stability. Benefiting from reversible dissolution-recrystallization behavior in water, the phosphors show outstanding recyclability, retaining around 80% PLQY and nearly unchanged decay dynamics after 15 cycles. In addition, structure-dependent solvent-responsive luminescence is observed, where DMSO treatment followed by drying induces distinct emission transformations. By integrating multicolor emission with stimulus-triggered optical transitions, a multilevel optical information encryption and decryption system with triple dynamic encryption is demonstrated, highlighting the potential of these materials for sustainable optical security and information storage applications.