Switchable photovoltaic and enhanced photoelectricity in a single PbS@CH3NH3PbI3 hybrid composite micro/nanowire

Abstract Organic-inorganic perovskite has an excellent response to visible light. For nanostructure perovskite, however, the fast recombination of photoexcited electron-hole pairs can be triggered by the affluent surface states, resulting in a decrease of photoresponsivity. Herein, PbS@CH3NH3PbI3 hybrid composite micro/nanowires, where PbS quantum dots (QDs) are uniformly dispersed in CH3NH3PbI3 matrix, are prepared by a fast liquid–solid growth of supersaturated solution with solvent evaporation. The hybrid composite structures noticeably improve the photoresponse to long wavelength light. For a single micro/nanowire-based device with a configuration of symmetrical two electrodes, more interestingly, a switchable photovoltaic effect can be successfully realized after being applied a relatively large fixed bias, and moreover the polarity of electrical signal can be reversed by inverting the direction of applied electric field, which stems from the reversible asymmetrical filling of QDs-related interface state traps near two electrodes by a large electric field-induced injection and extraction of holes. After being filled by holes, the ideal heterojunction of n-PbS and p-CH3NH3PbI3 can effectively separate photoexcited electron-hole pairs, resulting into an enhanced photoelectric response with rapid response and decay rate. Moreover, the emptied interface traps can induce a more obvious photovoltaic effect due to higher surface barrier. Based on the hybrid composite micro/nanostructures, not only photoelectric response can be improved, but also a switchable solar cell can be realized in the configuration of geometry symmetry with two-terminal electrodes.