High-Performance Lead-Free Cs3Bi2IxBr9–x Perovskite X-ray Detector Based on Anionic Engineering

Halide perovskites have garnered significant attention in the field of X-ray detection due to their tunable band gap, strong X-ray absorption capability, and superior optoelectronic properties. However, the high levels of dark current and noise are detrimental to low-dose and high-sensitivity X-ray detection and raise concerns about the stability of the detectors. Low-dimensional halide perovskites with a wide band gap have been proven to be a promising material to address these challenges. Here, a series of high-quality Cs3Bi2IxBr9–x single crystals with varying halide ion ratios were grown, and the relationship between phase transitions and changes in the anion composition were revealed. The wide band gap and high resistivity of these single crystals effectively reduce the dark current and noise levels of the detector, laying a solid foundation for detectors with nearly zero noise levels. As a result, X-ray detectors with a sensitivity of 1516 μC Gyair–1 cm–2 and a low detection limit (LoD) of 6.2 nGyair s–1 were obtained, which also exhibit exceptional stability under heat, voltage, and radiation stimuli.