Owing to their excellent optoelectronic properties, halide perovskite is very promising for photodetectors and other optoelectronic devices. Perovskite heterostructures are considered to be the key components for these devices. However, it is challenging to rationally synthesize those heterostructures. Here, we demonstrate that perovskite can be epitaxially grown on PbS by vapor transport, thereby creating an interesting CsPbBr₃-PbS heterostructure. Remarkably, photodetectors based on CsPbBr₃-PbS heterostructures exhibit visible to infrared broadband response with room temperature operation up to 2 μm. The room temperature detectivity higher than 1.0 × 10⁹ Jones was obtained in the 1.8- to 2-μm range. Furthermore, the p-n heterojunction exhibits a clear rectifying characteristic and enables detector to operate at zero-bias. Our study provides fundamentally contributes to establish the epitaxial growth perovskite heterostructures and demonstrate a materials platform for efficient perovskite-based optoelectronic devices.

The controlled synthesis of large and uniform gallium selenide (GaSe) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, vapor phase growth of high-quality monolayer GaSe nanosheets with multiple shape and size is achieved by tuning the Ga/GaSe ratio in the precursor. A theoretical model based on density functional theory calculations and kinetic Wulff construction theory describe the observed shape evolution of the GaSe nanosheets. Results show that the Ga/Se ratio plays a critical role in the evolution of the domain shape and size. Moreover, the as-grown GaSe nanosheets show improved performance with photoresponse time less than 0.7 ms and responsibility up to 3,000 A/W. This study presents a previously unexplored strategy for the controlled growth of two-dimensional (2D) GaSe nanosheets for promising applications in next-generation optoelectronics.