Enhanced photoresponse performance of self-powered UV–visible photodetectors based on ZnO/Cu2O/electrolyte heterojunctions via graphene incorporation

A photoelectrochemical cell can be used as a self-powered photodetector based on the photovoltaic effect. Here, we report an effective way to enhance the self-powered photoresponse performance of the ZnO nanowire arrays (NAs)/Cu2O photoanodes by introducing graphene interlayers. The self-powered photodetectors based on ZnO NAs/graphene (G)/Cu2O have large responsivities of 21.2 mA/W and 17.1 mA/W for ultraviolet (UV) and visible light, respectively, and fast rise and decay times (0.6 ms). Introduction of the Cu2O film improves the visible light-harvesting ability, and the step-like band alignment between ZnO and Cu2O benefits the separation of photoexcited carriers. Furthermore, the graphene interlayers also contribute to the carrier separation and transfer process because of their excellent charge collection capacity. The results demonstrate the ZnO/G/Cu2O heterojunction can be a promising configuration for self-powered UV–visible photodetecting.