Selective Epitaxy of PbSe/CsPbBr ₃ Nanosheet Heterostructures for High-Performance Photodetectors

Perovskite heterostructures have garnered significant attention, owing to their promising applications in optoelectronic devices. Nevertheless, the synthesis of high-quality heterostructures remains challenging due to the long diffusion length of the ions and the inherent instability of perovskite materials. In this study, we demonstrate the growth of high-quality vertical and lateral PbSe/CsPbBr3 nanosheet heterostructures via a precisely controlled two-step vapor-phase epitaxial process. Compared to existing PbSe/perovskite systems, this study not only achieves selective fabrication of both vertical and lateral heterostructures through a precise temperature control but also produces well-defined heterointerfaces with high crystalline quality. Furthermore, we reveal the critical roles of the thermal gradient and template thickness in governing the growth kinetics, providing new mechanistic insights into the epitaxial processes. Photoluminescence and time-resolved photoluminescence spectroscopy investigations confirmed efficient carrier transfer within these heterostructures. Furthermore, the photodetector fabricated from the lateral PbSe/CsPbBr3 core–shell nanosheet heterostructures exhibited a notable photoresponse across both visible (405 nm) and near-infrared (830 nm) wavelengths. Notably, the observed negative photoconductivity under 830 nm illumination reveals a light-induced conductance suppression effect. This work offers fundamental insights into the epitaxy of perovskite heterostructures and presents a viable platform for high-performance optoelectronics.