Coupling Localized Laser Writing and Nonlocal Recrystallization in Perovskite Crystals for Reversible Multidimensional Optical Encryption

The ability to generate and manipulate photoluminescence (PL) with high spatial resolution has been of primary importance for applications in micro‐optoelectronics, while the emerging metal halide perovskites offer novel material platforms where diverse photonic functionalities and fine structuring are constantly explored. Herein, micro‐PL patterns consisting of highly luminescent CsPbBr3 nanocrystals (NCs) in nonluminescent perovskite crystals are directly fabricated by focused femtosecond laser irradiation. Further modulation with a moisture field leads to the selective dissolution of the laser‐destabilized perovskite structures as revealed by density functional theory simulations, thus allowing for facile control of the reversible PL from the recrystallization of moisture‐induced CsPbBr3 NCs. By leveraging the coupled laser writing and moisture modulation, multimodal information encryption is realized by reversible encryption–reading and repeatable erasing–refreshing. This optical storage mechanism is also extended to 3D and 4D by realizing spatially and temporally resolved optical encryption. The coupled multifield modulation on perovskite crystals can enable potential applications in optical storage and encryption, and offer a novel solution for the creation and manipulation of localized PL structures with high temporal and spatial resolutions. Performing multifield modulation of coupled localized laser writing and nonlocal moisture treatment on metal halide perovskites crystals enables the creation and manipulation of localized photoluminescence for optical encryption from 2D to 3D and 4D, such as reversible encryption–reading, repeatable erasing–refreshing, and even spatially and temporally resolved reading with high resolution.