Optically Stimulated Ultraviolet‐C Luminescence for Solar Blind Imaging

ABSTRACT Optically stimulated luminescence (OSL) materials can convert trapped charge carriers into light under controllable light stimulation, thus holding great promise for diverse applications such as radiation dose detection and anti‐counterfeiting. Nevertheless, previous OSL signals are located in the visible or near‐infrared regions, overlapping seriously with the ambient light and thus hindering the application potential. Herein, we report a type of double perovskite structured phosphor, Cs ₂ NaYF ₆ :Pr ³⁺ , capable of emitting ultraviolet‐C (UVC) OSL. Upon X‐ray irradiation, Cs ₂ NaYF ₆ :Pr ³⁺ can store the excitation energy in terms of trapped charge carriers. In addition, it exhibits strong and persistent UVC luminescence under continuous light stimulation over a wide wavelength range or heating. By investigating the wavelength‐dependent stimulated luminescence phenomenon and trap‐clearing capability, we elaborate on the influence of excitation wavelength on UVC OSL. Leveraging the luminescent properties of Cs ₂ NaYF ₆ :Pr ³⁺ , we further demonstrate its potential application in tracking and marking in bright environments when exposed to sunlight irradiation. This work clarifies the generation mechanism of UVC OSL and its dependence on stimulation wavelength, thereby providing insights for the exploration of more UVC OSL materials.