High‐Responsive Photochromic High‐Entropy Materials for Image‐Matrix Encrypted Storage

ABSTRACT In the information era, secure storage and high‐throughput manipulation of massive image datasets face critical challenges. Inorganic photochromic (PC) media—promising candidates for optical storage—remain constrained by limited elemental diversity and stoichiometric flexibility, hindering performance breakthroughs. Conventional storage paradigms involving direct transcription of raw images onto PC layers are prone to security vulnerabilities. Herein, we fabricate a high‐entropy perovskite (HEP) ceramic achieving 58.1% PC contrast with sub‐second write/erase speeds. This superior performance is attributed to the tailored defect landscape dominated by oxygen vacancies, which facilitates efficient color‐center formation. Through precise Er 3 ⁺ site‐selective substitution, we reveal that B‐site occupancy synergistically optimizes dual‐mode PC and photoluminescence (PL)/upconversion luminescence (UCL). Leveraging this bifunctionality, we develop an image‐matrix encryption protocol that converts visual information into error‐correctable binary data matrices. The matrix‐based encryption architecture provides a security‐enhanced framework compatible with modern computing systems.