Color‐Center‐Driven Inorganic Photochromic Materials: Mechanisms, Classifications and Property Modulation

Inorganic photochromic materials, which undergo reversible changes in optical absorption and surface coloration upon exposure to external photo‐stimuli, have attracted sustained interest for their potential applications in advanced optical data storage, smart displays, secure information encryption, radiation detection, and sensing. Among the various mechanisms proposed to elucidate photochromism in inorganic compounds, color centers associated with lattice defects are widely recognized as the primary origin. In this mini‐review, recent progress in inorganic photochromic materials is discussed from the perspective of color‐center formation and modulation. A unified framework based on photoexcitation, carrier trapping, and carrier release is first introduced to outline the physical principles underlying defect‐mediated photochromism. Subsequently, representative material systems are reviewed according to the dominant origins of photochromically active color centers, including oxygen vacancies, non‐oxygen anion‐related defects, and cation‐related defects, with emphasis on their characteristic photochromic responses, excitation selectivity, and stability. Furthermore, defect engineering strategies for regulating photochromic performance are summarized, such as compositional control, trap‐depth modulation, synthesis‐atmosphere regulation, and coloration‐composite approaches. These strategies enable precise tuning of response kinetics, stability, and color diversity while preserving the fundamental defect‐mediated mechanism. Finally, current challenges and prospective research directions in color‐center‐driven inorganic photochromism are briefly discussed.