Defect‐Engineered Multicolor Persistent Luminescent Germanate Glass Ceramic for Advanced Anti‐Counterfeiting and x‐Ray Imaging

Persistent luminescent (PersL) materials exhibit promising application prospects in night displays, information storage, and background‐free imaging. However, the realization of continuously tunable multicolor PersL within a single material remains a formidable challenge. This work presents a novel germanate glass and glass ceramic (GC) system with PersL colors continuously tunable from blue‐white to yellow. DFT calculation revealed the electron capture and release mechanisms associated with defects (vacancies and anti‐site defects) during multicolor luminescence, and further elucidated the evolution of defect states during glass crystallization. By virtue of their excitation‐, time‐, and temperature‐dependent PersL characteristics, the application potential of these materials in multidimensional advanced optical anti‐counterfeiting is rationally designed and verified. Furthermore, Mn 2 + ‐doped GCs with luminescence colors continuously tunable from green to red were successfully fabricated. Under x‐ray excitation, their scintillation luminescence intensity reaches 123.3% of that of BGO crystal, with an imaging resolution of 20 LP/mm, enabling clear observation of the internal circuit layout of electronic components. This work not only provides a multifunctional luminescent platform for advanced anti‐counterfeiting and x‐ray imaging, but also offers new insights into the rational design of defect‐mediated luminescent materials and the exploration of luminescence mechanisms.