Laser Writing of Inorganic Perovskite Films for Anticounterfeiting Applications

Abstract

Advanced fluorescent anti-counterfeiting technologies have garnered widespread attention due to the insufficient security of traditional anti-counterfeiting methods. Addressing the ongoing demand for more secure anti-counterfeiting methods, we pioneered a simple and effective strategy for the on-demand fabrication of CsPbBr₃ nanocrystalline patterns via direct laser writing on CsPbBr_1.8I_1.2 perovskite thin films. The resulting films were comprehensively characterized in terms of morphology, structure, elemental composition, and optical properties. Our investigation reveals that mild laser irradiation induces a reaction between iodide ions and ambient oxygen, leading to iodide depletion and local bromide enrichment with replacing the lattice positions of these iodide vacancies. This halide exchange facilitates the formation of CsPbBr₃ nanocrystals, which exhibit bright green luminescence under 365 nm UV excitation. At higher laser intensities, blue luminescence can also be achieved, attributed to the smaller crystal sizes. By leveraging programmable design, we successfully generate green- and dual-emissive patterns within otherwise non-luminescent CsPbBr_1.8I_1.2 films, offering a promising route for optical anti-counterfeiting applications. This work demonstrates a novel, laser-assisted technique for the controlled creation of fluorescent security features.

Keywords

Photophysics / Photochemistry / Fluorescence / Lead halide perovskite / CsPbBr₃ / Laser writing / Anticounterfeiting / Thin films

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