Zero‐Dimensional Cs 3 Cu 2 I 5 Perovskite Single Crystal as Sensitive X‐Ray and γ‐Ray Scintillator

Low‐dimensional halide perovskites with highly efficient luminescent properties have attracted huge attention in optoelectronic and radiation detection applications in recent years. Herein, a highly efficient 0D Cs 3 Cu 2 I 5 perovskite crystal is presented for X‐ray and γ‐ray detection that can be easily grown from the melt by the Bridgman method. The crystal structure of Cs 3 Cu 2 I 5 belongs to an orthorhombic system with a space group of Pnma . The Cs 3 Cu 2 I 5 crystal is nonhygroscopic and self‐absorption free due to a large Stokes shift of 120 nm originated from its self‐trapped exciton emission. Its scintillation emission centers at 440 nm with a principal decay time of 967 ns. The Cs 3 Cu 2 I 5 crystal not only demonstrates a high scintillation yield of about 32 000 photons MeV −1 and an extremely low afterglow of 0.03% at 10 ms under X‐ray radiation, but also possesses a high light yield of 29 000 photons MeV −1 with an excellent energy resolution of 3.4% at 662 keV under γ‐ray radiation.