Suppressed Ion Migration in Tin Halide Perovskites for Stable X‐Ray Detectors with Low Dark Current Drift

Abstract Ion migration is a major factor affecting the operational stability of perovskite X‐ray detectors, especially under the necessary high working bias. To address this issue, lead‐free tin halide perovskites (FASnI 3 ) being pioneered with the robust Sn─I bond for X‐ray detection. It is observed that the incorporation of propylamine hydroiodide (PAI) to FASnI 3 ‐PAI films can increase activation energy for ion migration (752.18 meV), thereby enhancing the operational stability of X‐ray detectors. The devices based on FASnI 3 ‐PAI demonstrate a significant reduction in dark current drift (1.14 × 10 −16 A cm −1 V −1 s −1 ), with values two orders of magnitude lower than those observed in lead halide perovskites (2.40 × 10 −14 A cm −1 V −1 s −1 ). Moreover, the FASnI 3 ‐PAI films exhibit enhanced film crystallinity, reduced trap density, and improved mobility‐lifetime product, resulting in a high sensitivity of 5535 µC Gy air −1 cm −2 and an ultralow detection limit of 7.95 nGy air s −1 . Significantly, high‐contrast X‐ray imaging has also been successfully achieved.