Laser-Induced Fabricationof Multicolor PerovskiteQuantum Dot Patterns with Multiple Information Encryption Modes

The development of patterned metal halide perovskite quantum dots (MHP QDs) has become an important strategy to explore new functionalities and applications in optoelectronics. Herein, a laser-induced technology is developed to fabricate multicolor MHP QD patterns to achieve multiple information encryption modes. To precisely control the synthesis reactions, PbBr₂ and CsBr, the precursors of CsPbBr₃ QDs, are separately coated on the donor glass and target substrates and stacked into a donor-PbBr₂–CsBr-target structure. A femtosecond laser is focused at the interface of PbBr₂ and CsBr to induce localized ionic transportation and reaction so that CsPbBr₃ QDs are precisely synthesized at the laser spot. By applying the environmental lability and low formation energy of perovskites, the PL emission of the laser-synthesized CsPbBr₃ QDs can be reversibly eliminated under a moisture environment and recovered <i>in situ</i> by laser scanning for many cycles. This reversible PL behavior is attributed to the phase transformation between CsPbBr₃ and CsPb₂Br₅ induced by the repeated laser irradiation and moisture treatment and is promising for applications in information encryption, anticounterfeit, and optical data storage. Furthermore, MHP patterns with multiple color emissions are synthesized by adjusting the precursors, demonstrating the flexibility of the developed technology in color tuning of MHP QDs.