Ultrabright and Highly Efficient All‐Inorganic Zero‐Dimensional Perovskite Scintillators

Abstract Low‐dimensional halide perovskites with excellent luminescent properties have become leading candidates for optoelectronic and radiation‐detection applications. In this work, Tl cation is incorporated into 0D perovskite Cs 3 Cu 2 I 5 host and an ultrabright and efficient scintillator is developed for X‐ray and γ‐ray detection. The Tl‐doped Cs 3 Cu 2 I 5 crystals exhibit a high photoluminescence quantum efficiency of 79.2%. The radioluminescence emission of Cs 3 Cu 2 I 5 :Tl crystal under X‐ray excitation consists of a self‐trapped exciton emission at 440 nm and a Tl‐related emission at 510 nm at room temperature. With optimized Tl doping, the Cs 3 Cu 2 I 5 not only demonstrates about five‐times enhanced steady‐state scintillation yield up to 150 000 photons/MeV and an improvement of X‐ray detection limit from 103.6 to 66.3 nGy s −1 , but also maintains an extremely low afterglow of 0.17% at 10 ms after X‐ray cut‐off. The Cs 3 Cu 2 I 5 :Tl also possess a remarkable energy resolution of 3.4% at 662 keV and an ultrahigh light yield of 87 000 photons/MeV under 137 Cs γ‐ray radiation.