Library of Two-Dimensional Hybrid Lead Halide Perovskite Scintillator Crystals

Two-dimensional (2D) hybrid lead halide perovskites are potential candidates for high light yield scintillators as they have small band gaps between 3 and 4 eV and large exciton-binding energy. Here, we discuss the scintillation properties from a total of 11 organic/inorganic hybrid perovskite crystals with two already reported crystals, (PEA)2PbBr4 and (EDBE)­PbBr4. Their photoluminescence and X-ray luminescence (XL) spectra are dominated by narrow and broad band emissions, and they correspond to free exciton and self-trapped exciton, respectively. The lifetimes derived from time-resolved XL strongly vary from 0.6 to 17.0 ns. These values make this type of compound among the fastest scintillators. For the light yield derived from the XL, we found that only (PEA)2PbBr4, (EDBE)­PbBr4, and (BA)2PbBr4 crystals have light yields between 10,000 and 40,000 photons/MeV. The mechanisms for thermal quenching and afterglow are discussed in order to optimize the light yields. With gamma-ray excitation, we reported the best energy resolution of 7.7% at 662 keV with excellent proportionality. Finally, this study paves the way toward the ultimate high light yield and fast scintillators for medical and homeland security applications.