A New Polar Lead‐Free Hybrid Halide X‐Ray Scintillator

X‐ray imaging serves a critical role across diverse sectors, including medical diagnostics, industrial surveillance, security, and space exploration. This study delves into the unique properties of a novel polar crystal, [FMPPA]ZnBr 4 (FMPPA = protonated 3‐fluoro‐4‐(4‐methyl‐1‐piperazinyl)aniline), characterized by a 0D metal halide structure. This crystal features [ZnBr 4 ] 2− tetrahedra and A‐site organic amine ion [FMPPA] 2+ rings. With a high photoluminescence quantum yield (≈70%) and minimal self‐absorption, [FMPPA]ZnBr 4 demonstrates exceptional scintillation performance under X‐ray excitation, producing 29300 ± 600 photons MeV −1 and achieving a low detection limit of 0.352 µGy air s −1 , surpassing conventional 3D perovskite nanocrystals. Beyond superior performance, this scintillator meets the demand for efficient X‐ray imaging light emitters. Moreover, it consistently achieves ≈12.5 lp mm −1 high‐resolution X‐ray imaging. Additionally, [FMPPA]ZnBr 4 exhibits a nonlinear optical response, surpassing the benchmark KH 2 PO 4 by 1.8 times. This investigation introduces a new structure framework, paving the way for the development of integrated optoelectronic materials with both nonlinear and linear optical properties.