High‐Performance and Self‐Powered X‐Ray Detectors Made of Smooth Perovskite Microcrystalline Films with 100 μm Grains

Abstract Perovskite single crystals and polycrystalline films have complementary merits and deficiencies in X‐ray detection and imaging. Herein, we report preparation of dense and smooth perovskite microcrystalline films with both merits of single crystals and polycrystalline films through polycrystal‐induced growth and hot‐pressing treatment (HPT). Utilizing polycrystalline films as seeds, multi‐inch‐sized microcrystalline films can be in situ grown on diverse substrates with maximum grain size reaching 100 μm, which endows the microcrystalline films with comparable carrier mobility‐lifetime ( μτ ) product as single crystals. As a result, self‐powered X‐ray detectors with impressive sensitivity of 6.1×10 4 μC Gy air −1 cm −2 and low detection limit of 1.5 nGy air s −1 are achieved, leading to high‐contrast X‐ray imaging at an ultra‐low dose rate of 67 nGy air s −1 . Combining with the fast response speed (186 μs), this work may contribute to the development of perovskite‐based low‐dose X‐ray imaging.