In Situ Crystal Growth and Fusing-Confined Engineering of Quasi-Monocrystalline Perovskite Thick Junctions for X-ray Detection and Imaging.

Metal halide perovskites exhibit great promise for utilization in X-ray detection owing to their excellent optoelectronic properties and high X-ray attenuation capabilities. However, fabricating large-area thick films for high-performance perovskite X-ray detection remains challenging. This study develops an in situ crystal growth and fusing-confined approach to prepare high-quality, large-scale perovskite quasi-monocrystalline thick junctions. The perovskite crystals are grown in situ using a highly concentrated perovskite colloidal solution in 2-methoxyethanol. Introducing methylammonium chloride enhances grain reorganization during in situ growth and fusing-confined processes, effectively reducing grain boundaries and surface defects. This allows for the preparation of quasi-monocrystalline thick junctions of large grains (>100 μm) with high crystallinity, uniform orientation, and vertical penetration across the film thickness. Additionally, the carrier mobility and lifetime of the thick junctions are significantly enhanced. The optimized MAPbI detectors demonstrate an X-ray sensitivity of 2.6 × 10 μC Gy cm and an exceptionally low detection limit of 1 nGy s. Furthermore, inspired by a honeycomb structure, these detectors realize X-ray imaging in 64 × 64 pixels through a pixelated separation design, effectively reducing the charge-sharing effect. This study offers valuable insights into the preparation of large-scale perovskite quasi-monocrystalline thick junctions for highly sensitive X-ray detection and imaging applications.