Recent developments in deep-ultraviolet phosphors for multistimulated luminescence

Inorganic optical materials capable of emitting ultraviolet photons, especially in the deep-ultraviolet (DUV) regions spanning ultraviolet-C (UVC: 100 to 280 nm) and ultraviolet-B (UVB: 280 to 315 nm), have gained ever-increasing attention recently due to their potential applications in sterilization, disease treatment, covert communication, and background-free imaging. We highlight the rapid growth of this emerging field since its inception in 2018, with a focus on DUV emission under thermal, optical, and mechanical stimulations. A central theme of this review is the critical importance of rational material design, particularly the strategies for tuning emission wavelengths and intensities by modulating trap distributions and local crystal fields. We also critically assess the state-of-the-art applications, which capitalize on the unique advantages of DUV photons, namely, their immunity to interference from ambient light. Despite promising progress, the field faces challenges, such as insufficient brightness and a lack of universal design principles, which currently limit widespread implementation. To overcome these barriers to practical deployment, we advocate for a paradigm shift from serendipitous discovery to knowledge-driven design by systematically integrating machine learning and advanced multimodal in situ characterization to unveil universal trap dynamics. By synthesizing the current understanding, we expect to provide a roadmap for developing high-performance multistimulated DUV materials.