Room-Temperature-Grown FAPb0.5Sn0.5I3 Polycrystalline Thick Films for Self-Powered X-Ray Detectors With High Sensitivity and Low Detection Limit

Perovskite polycrystalline thick films are promising for x-ray detection and imaging, yet the simultaneous realization of high sensitivity and a low detection limit remain difficult due to the trade-off between transport and ion migration. Herein, we report the preparation of FAPb 0.5 Sn 0.5 I 3 (FA = CH(NH 2 ) 2 ) perovskite polycrystalline thick films with negligible Sn 2+ oxidation at room temperature by solvent engineering. The as-prepared films deliver exceptional carrier transport properties, as evidenced by an ultralong carrier diffusion length ( L D ) of 58 µm. Moreover, the high ion migration activation energy ( E a ) of 0.67 eV endows the detectors with suppressed dark current and a minimal drift of 2.09 × 10 −5 nA cm −1 s −1 V −1 . Collectively, these merits result in self-powered x-ray detectors with both high sensitivity of 3.88 × 10 3 µC Gy air −1 cm −2 and an ultralow detection limit of 0.93 nGy air s −1 . Our work may promote the development of stable and low-dose-rate perovskite x-ray imaging.