Lead‐Free Halide Rb2CuBr3 as Sensitive X‐Ray Scintillator

Abstract Scintillators are widely utilized for radiation detections in many fields, such as nondestructive inspection, medical imaging, and space exploration. Lead halide perovskite scintillators have recently received extensive research attention owing to their tunable emission wavelength, low detection limit, and ease of fabrication. However, the low light yields toward X‐ray irradiation and the lead toxicity of these perovskites severely restricts their practical application. A novel lead‐free halide is presented, namely Rb 2 CuBr 3 , as a scintillator with exceptionally high light yield. Rb 2 CuBr 3 exhibits a 1D crystal structure and enjoys strong carrier confinement and near‐unity photoluminescence quantum yield (98.6%) in violet emission. The high photoluminescence quantum yield combined with negligible self‐absorption from self‐trapped exciton emission and strong X‐ray absorption capability enables a record high light yield of ≈91056 photons per MeV among perovskite and relative scintillators. Overall, Rb 2 CuBr 3 provides nontoxicity, high radioluminescence intensity, and good stability, thus laying good foundations for potential application in low‐dose radiography.