Fabrication of perovskite vertical heterojunction and flexible single-crystal arrays using droplet-evaporated crystallization method

Lead halide perovskites are promising candidates for photodetectors owing to their excellent photoelectric properties. Compared to their pure phases, perovskite heterojunctions exhibit tunable carrier transport properties, which can significantly enhance the performance of optical and optoelectronic applications. Given that the quality of semiconductor heterojunctions is directly correlated with device performance, it is imperative to develop facile and efficient fabrication methods to obtain high-quality all-inorganic lead halide perovskite heterojunctions. Here, we report a hybrid/all-inorganic single crystal heterojunction photodetector, which was constructed by epitaxially growing the MAPbBr(3-x)Cl(x) (X = 0.37, 0.76) film on a CsPbBr3 substrate using the droplet-evaporated crystallization method. MAPbBr(3-x)Cl(x) (X = 0.37, 0.76) single-crystal arrays were also successfully obtained by adding a mask to the substrate using this method, which may fabricate perovskite-based flexible array devices. The formation of the MAPbBr(3)/CsPbBr3 (MAPB/CPB) heterojunction drastically enhanced the photoresponse properties of the Au/CsPbBr3/Au (Au/CPB/Au) device. Remarkably, the Au/MAPB/CPB/Au detector achieved a responsivity of 3.68 A W-1 with a high carrier mobility of 43.5 cm(2) V-1 s(-1) under 20 V mm(-1) using 465 nm light. The dark current drift degree was also suppressed. Our research provides a simple and cost-effective method for enhancing the performance of photodetectors, which can be extended to the construction of other single-crystal heterojunctions and flexible single-crystal arrays.