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

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 × 104 μC Gyair−1 cm−2 and low detection limit of 1.5 nGyair s−1 are achieved, leading to high-contrast X-ray imaging at an ultra-low dose rate of 67 nGyair 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.