Lateral Structured Phototransistor Based on Mesoscopic Graphene/Perovskite Heterojunctions

Due to their outstanding optical properties and superior charge carrier mobilities, organometal halide perovskites have been widely investigated in photodetection and solar cell areas. In perovskites photodetection devices, their high optical absorption and excellent quantum efficiency contribute to the responsivity, even the specific detectivity. In this work, we developed a lateral phototransistor based on mesoscopic graphene/perovskite heterojunctions. Graphene nanowall shows a porous structure, and the spaces between graphene nanowall are much appropriated for perovskite crystalline to mount in. Hot carriers are excited in perovskite, which is followed by the holes' transfer to the graphene layer through the interfacial efficiently. Therefore, graphene plays the role of holes' collecting material and carriers' transporting channel. This charge transfer process is also verified by the luminescence spectra. We used the hybrid film to build phototransistor, which performed a high responsivity and specific detectivity of 2.0 × 10³ A/W and 7.2 × 10¹⁰ Jones, respectively. To understand the photoconductive mechanism, the perovskite's passivation and the graphene photogating effect are proposed to contribute to the device's performance. This study provides new routes for the application of perovskite film in photodetection.