Self-Powered Lateral Heterojunction Photodetectors: Unveiling Ultraviolet Sensitivity via the RbCu₂I₃ Microwire and the MAPbBr₃ Film with Innovative Engineering

Assembling perovskites into heterojunctions enables multifunctional high-performance photodetectors. Compared with vertical heterojunctions, lateral heterojunctions enhance the optoelectronic performance of devices due to the direct contact between the photosensitive layer and light, reducing light reflection losses. However, the fabrication of all-perovskite lateral heterojunctions is challenging through a solution method. The first perovskites formed are easily dissolved by the solvent of the second precursor, hindering their further application in photodetectors. In this study, we have developed a preparation process for the lateral microwire (MW)/film heterojunction and the Ag/RbCu2I3 MW/MAPbBr3 film/indium tin oxide heterojunction photodetector by utilizing an optical fiber-based physical transfer step. Thanks to the high-quality RbCu2I3 MW/MAPbBr3 film lateral heterojunction, the device demonstrated excellent optoelectronic performance at 0 V bias voltage, with a responsivity of 0.79 mA·W–1 and a detectivity of 5.34 × 1012 Jones under 339 nm radiation. In addition, the device exhibited consistent and rapid response times under 355 and 450 nm irradiation. This optical fiber-based physical transfer method provides a self-powered light detection strategy for the preparation of all-perovskite lateral heterojunctions.