Ion\nLeakage Current\nControl for Polycrystalline Metal\nHalide Perovskite Direct X‑ray Detectors

Metal\nhalide perovskites have emerged as promising materials\nfor\nX-ray detection due to their high X-ray attenuation coefficients,\ndefect tolerance, and suitability for large-area, low-temperature\nfabrication. However, the intrinsic high ion conductivity of these\nmaterials presents challenges, such as high dark current density and\ncurrent drift, which impair the stability and sensitivity of perovskite\nX-ray detectors. This study introduces an approach to mitigating these\nissues by incorporating 2,2,3,3,3-pentafluoropropylamine hydrochloride\n(PFH) into polycrystalline MAPbI<sub>3–<i>x</i></sub>Cl<sub><i>x</i></sub> films using a one-step blade-coating\nmethod. PFH aggregates at grain boundaries, raising local vacuum energy\nlevels and passivating surface defects, thereby reducing ion conductivity\nwithout affecting electron conductivity. As a result, this approach\nsignificantly reduces the dark current and enhances sensitivity, achieving\na low detection limit of 14.7 nGy<sub>air</sub>/s. Additionally, it\nimproves signal stability, consistency, and response speed of the\ndetector. These findings suggest that PFH is a promising additive\nfor advancing the performance and practical application of polycrystalline\nmetal halide perovskite-based X-ray detectors.