Epitaxial Welding of 3D and 2D Perovskite Single Crystals for Direct-Indirect Energy-Conversion X-ray Detection and Imaging

Perovskite single crystals (SC) with strong X-ray absorption and low fabrication costs are expected to be the next generation of materials for X-ray detection. However, the low resistivity and serious ion migration of three-dimensional (3D) perovskites lead to a high leakage current and response drift as well as the low carrier mobility and radiation luminescence (RL) of two-dimensional (2D) perovskites, resulting in a low response output of the detector. In this study, we successfully combined the high carrier mobility of 3D perovskites with the high resistivity and low ion migration of 2D perovskites by the epitaxial welding of 3D and 2D SCs. In addition, the RL of the 2D SC sandwich layer in the formed 3D/2D/3D SC was recovered by the 3D SC, resulting in an enhanced energy-conversion efficiency for X-ray detection. Therefore, the 3D/2D/3D SC X-ray detectors achieved a 566% improvement in sensitivity and an ultralow detection limit of 14.2 nGy s(-1). Owing to the excellent stability of the 3D/2D/3D SC, the detector still maintained its original response after 30,000 s. All of these properties enabled the detector to provide a high spatial resolution of 13.8 lp mm(-1) in X-ray imaging. This study provides a new strategy for designing stable and sensitive X-ray detectors.