Synthesis and Characterization of All‐Inorganic Perovskite CsEuBr3 Single‐Crystal Scintillator

All‐inorganic halide perovskites appear as a promising class of scintillators for radiation detection applications due to their excellent optoelectronic properties. Herein, a self‐activated perovskite CsEuBr 3 single crystal is developed as an efficient X‐ and γ‐ray scintillator. Single crystals of CsEuBr 3 are grown by the Bridgman method. The phase structure, stability, photophysics properties, and scintillation performance of CsEuBr 3 single crystals are studied. Under X‐ray irradiation, its emission peaks at 445 and 510 nm, associated with Eu 2+ 5 d –4 f and defect‐related emission, respectively, are studied. Under 137 Cs gamma irradiation, it has a decent light yield of 22 000 ± 2000 photons MeV −1 and an energy resolution of 6.2 ± 0.4% at 662 keV with a scintillation decay of 510 ns.