Structure‐Function Integration in 2D Hybrid Perovskite for Fast Neutron and Gamma Ray Discrimination

Abstract Efficient discrimination between fast neutrons and gamma rays is crucial yet challenging for radiation detection. Here, the successful growth of large‐size, high‐quality 2D organic–inorganic hybrid perovskite single crystals, (GABA) 2 PbBr 4 , via an in situ seed‐assisted cooling method is reported. This material integrates hydrogen‐rich GABA cations with heavy‐atom lead halide layers, offering strong excitonic emission, efficient γ‐ray absorption, and fast neutron sensitivity. X‐ray diffraction reveals highly oriented crystals along the (004) plane with a narrow full width at half maximum (FWHM) of 12.81″. Optical characterizations indicate a wide bandgap (≈3.0 eV), sharp excitonic emission, and prominent self‐trapped exciton behavior, supported by transient and temperature‐dependent photoluminescence. The crystals exhibit an energy resolution of 9.0% at 662 keV and a high light yield of 10 695 ph MeV −1 . Notably, superior neutron/gamma pulse shape discrimination (PSD) is achieved with a maximum figure‐of‐merit (FOM) of 1.74, enabling clear signal separation. Additionally, flexible composite scintillation films based on (GABA) 2 PbBr 4 demonstrate high‐resolution X‐ray imaging up to 10 LP mm −1 . These results highlight the potential of (GABA) 2 PbBr 4 as a multifunctional scintillator for advanced radiation detection and imaging applications.