Liquid-Phase Epitaxial Growth of Large-Area MAPbBr_3–<i>n</i>Cl_<i>n</i>/CsPbBr₃ Perovskite Single-Crystal Heterojunction for Enhancing Sensitivity and Stability of X-ray Detector

Abstract

Metal halide perovskites have emerged as next-generation semiconductors for X-ray detection because of their excellent photoelectric properties. However, severe ion migration in three-dimensional (3D) halide perovskites usually causes dark current drift in radiation detectors, especially in high electric fields. Here, we report a liquid-phase epitaxial method based on inverse-temperature crystallization (ITC), with which a hybrid/all-inorganic 3D perovskite single-crystal heterojunction is constructed, using an orientated CsPbBr3 single crystal as a substrate. MAPbBr3–nCln/CsPbBr3 single-crystal heterojunctions and single-crystal arrays (through the addition of a mask onto the substrate) with good lattice matching were successfully constructed, laying the foundation for high-performance X-ray detectors. In particular, the MAPbBr3/CsPbBr3 heterojunction drastically enhances the X-ray response of the CsPbBr3 single crystal, with a record-high sensitivity of 2.0 × 105 μC Gyair–1 cm–2 and lowest detection limit of 96 nGyair s–1 for 120 keV hard X-ray detection. Moreover, the dark current drift caused by ion migration is suppressed to 3.92 × 10–4 nA cm–1 s–1 V–1 even in a high reverse electric field of −125 V mm–1. Based on the superior detection performance, it is confirmed that a robust and uniform X-ray imaging detector with good resolution was successfully devised using the heterojunction. Our study provides a simple strategy for constructing perovskite single-crystal heterojunction films and arrays that effectively suppress ion migration that otherwise occurs in 3D halide perovskite single crystals to enable the creation of robust ultrasensitive X-ray detection and imaging systems.