Quasi‐2D Perovskite Thick Film for X‐Ray Detection with Low Detection Limit

Abstract Organic‐inorganic hybrid perovskites have demonstrated excellent performance in converting X‐ray photons to electrical signals with high detectivity and sensitivity. Solution‐processed large‐area perovskite polycrystalline thick film is promising for scalable X‐ray flat panel detection imaging. However, ionic migration is severe due to the numerous grain boundaries and pinholes in the thick films, resulting in a large dark current and serious baseline drift. Herein, a new strategy is proposed to suppress the ion migration by inserting 2D Ruddlesden–Popper layer into the 3D perovskite film. The quasi‐2D perovskite thick films exhibit lower defects density, suppressed ion migration, and higher thermal stability compared to their 3D counterpart. Based on these advantages, the quasi‐2D perovskite‐based X‐ray detector shows a sensitivity of 10 860 µC Gy air −1 cm −2 with a stable dark current and photocurrent response. Impressively, the extra‐low detection limit of 69 nGy air s −1 is the lowest in all those reported polycrystalline film‐based detectors. The quasi‐2D film is believed to be a very promising choice for digital flat detectors for sensitive radiation detection and low‐dose dosimeter.