Beyond the visible: metal-ion-doped inorganic UV phosphors for advanced photonics.

Inorganic ultraviolet (UV) luminescent materials doped with metal ions (including rare-earth and heavy main-group metal ions) exhibit distinctive electronic transitions, excellent photostability, and tunable emission characteristics, making them highly promising for applications in optoelectronics, environmental remediation, and biomedicine. Recent progress in metal-ion-doped UV-emitting systems, such as persistent luminescence, upconversion luminescence, and mechanoluminescence, has significantly expanded the possibilities for UV light generation and utilization. This review provides a comprehensive and systematic overview of the luminescence mechanisms, recent advances, and emerging applications of these materials, structured according to dominant luminescence modes and supplemented by spectral classifications. First, UV persistent luminescence materials are critically examined with emphasis on optimization strategies and future research opportunities. Next, the UV upconversion luminescence systems are reviewed, highlighting mechanistic insights and breakthrough achievements. The discussion then turns to UV mechanoluminescent materials, focusing on their ability to emit light under mechanical stimulation and on recent progress in material design and device integration. Applications of these metal-ion-doped inorganic UV phosphors across different spectral regions are further analyzed under the guiding principle that "performance dictates application". Finally, key challenges and future directions are outlined to provide a forward-looking perspective for advancing inorganic UV luminescent materials.