Recent years, organic-inorganic hybrid perovskites (OIHPs) have been widely used in applications, such as solar cells, lasers, light-emission diodes, and photodetectors due to their outstanding optoelectronic properties. Nowadays photodetectors based on perovskite films (PFs) suffer from surface and interface traps, which result from low crystalline quality of perovskite films and lattice mismatch between perovskite films and substrates. Herein, we fabricate MAPbI₃-(MA = CH₃NH₃) single-crystal films (SCFs) on MAPbBr₃single crystal substrates in MAPbI₃precursor solution during crystallization process via solution-processed epitaxy. Benefit from the good lattice matching, epitaxial MAPbI₃SCFs with high crystallinity and smooth morphology are of comparable quality to MAPbI₃PSCs and are of better quality than MAPbI₃polycrystalline films. Here we report that epitaxial MAPbI₃SCFs have a low trap density of 5.64×10¹¹cm^–3and a long carrier lifetime of 11.86 μs. In this work, photodetector based on epitaxial MAPbI₃single-crystal film (SCF) exhibits an excellent stability of a long-term stable response after 120 days, a fast response time of 2.21 μs, a high responsivity of 1.2 A W^–1and a high detectivity of 3.07 ×10¹²jones.

The epitaxially fabricated MAPbBr₃/Bi³⁺-doped MAPbCl₃PSCs pN heterojunction shows advanced X-ray detection performance with decreased dark current density and faster response time under relatively high external reverse voltage.