Charge transport manipulation of lead‐free perovskite A ₃ Sb ₂ X ₉ single crystal for stable and sensitive x‐ray detection

Compared with three‐dimensional (3D) perovskites, low‐dimensional perovskites can effectively enhance device stability and reduce leakage current due to the shielding effect of A‐site cations and high resistivity, thus showing broad application prospects in the field of high‐energy radiation detection. In this study, high‐quality lead‐free A 3 Sb 2 X 9 type single crystals (SCs) with large size are grown via a solution method. The manipulation mechanism of charge transport in these low‐dimensional perovskite SCs by ion radius, coordination ability, and charge distribution characteristics is systematically investigated. Furthermore, the collaborative optimization mechanism of x‐ray detection performance through crystal structure design and charge transport performance manipulation is elaborately revealed, which provides an important foundation for designing high‐quality and low‐toxicity perovskite SCs to achieve high signal‐to‐noise ratio (SNR) x‐ray detectors. Therefore, under the premise of maintaining superior stability and high resistivity, the optimized lead‐free low‐dimensional perovskite SCs achieve comparable detection performance to that of lead‐based perovskites. Specifically, the fabricated SC x‐ray detectors exhibit high resistivity (10 11 Ω cm), large μτ product (7.9 × 10 −3 cm 2 V −1 ), high detection sensitivity (3073 μC Gy −1 cm −2 ), ultra‐low detection limit (0.37 nGy s −1 ), and negligible dark current drift (6.8 × 10 −8 nA cm −1 s −1 V −1 ). This rare combination of superior properties enables the SC detector to achieve high‐resolution (7.5 lp mm −1 ) x‐ray imaging.