Direct Laser Patterning of Stable All‐Inorganic Perovskite Nanocrystals for Stimuli‐Responsive Multimodal Fluorescent Anticounterfeiting Devices and Information Security

ABSTRACT Recently, metal halide perovskite materials have shown remarkable progress in next‐generation LEDs, anticounterfeiting, and imaging applications. However, achieving uniform, high‐quality micron‐sized perovskite fluorescent patterns remains a critical challenge, since they are prone to degrade in photoresist (PR), polar solvents, and intense laser irradiation. There are a few research articles on perovskite bulk films, but patterning of perovskite nanocrystals (PNCs) and their application have not been extensively explored. In this regard, we synthesized double‐coated CsPbX 3 (X = Br, I) PNCs via a ligand‐assisted reprecipitation method and studied photophysical properties. We introduce rapid emission recovery of thermally quenched PNC films via 2‐Methylimidazole treatment. We fabricated flexible, hard‐to‐replicate PNC patterns using continuous‐wave direct laser patterning (DLP) technology. We developed ∼10 µm‐size green‐emitting arrays from the mixture of SU8 PR and CsPbBr 3 PNCs, which exhibited multimodal anticounterfeiting properties. However, the non‐uniform luminescent arrays and chemical instability of red‐emitting CsPbI 3 PNCs within SU8 limit their applications. We present a PR‐free DLP process that enables patterning of PNC films with dimensions of ∼40 µm. We also introduce a 4D “stimuli‐responsive binary information cycle” using CsPbI 3 PNCs, involving UV excitation, microscope resolution, thermal erasure, and chemical recovery. These results establish a versatile platform for practical, stimuli‐responsive anticounterfeiting applications.