Defect-Assisted High Photoconductive UV-Visible Gain in Perovskite-Decorated Graphene Transistors

Recent progress in the synthesis of high stability inorganic perovskite nanocrystals (NCs) has led to their increasing use in broadband photodetectors. These NCs are of particular interest for the UV range as they have the potential to extend the wavelength range of photodetectors based on traditional materials. Here we demonstrate a defect-assisted high photoconductive gain in graphene transistors decorated with all-inorganic cesium lead halide perovskite NCs. The photoconductive gain in the UV-vis wavelength range arises from the charge transfer between the NCs and graphene and enables observation of high photoconductive gain of 10(6) A/W. This is accompanied by a giant hysteresis of the graphene resistance that is strongly dependent on electrostatic gating and temperature. Our data are well described by a phenomenological macroscopic model of the charge transfer from bound states in the NCs into the graphene layer, providing a useful tool for the design of high-photoresponsivity perovskite/graphene transistors.