Self-powered UV–visible photodetectors based on ZnO/graphene/CdS/electrolyte heterojunctions

Abstract

A novel ZnO nanowire arrays (NAs)/graphene(G)/CdS/electrolyte heterojunction was successfully prepared via a simple three-step synthesis method when applied for photoelectrochemical type self-powered UV–visible photodetectors. Under zero bias, the responsivities of the self-powered UV–visible photodetectors on the basis of ZnO NAs/G/CdS/electrolyte heterojunctions are 27.3 mA/W and 4.3 mA/W for the UV and visible light, respectively, with fast rise and decay times (5 ms). Graphene improves the response of ZnO NAs to UV and visible light to a certain extent owing to its excellent charge-collecting ability and the acceleration of carrier separation and transference. After covering photosensitive CdS nanoparticles, the response to visible light is greatly increased because of the type II energy band structure of ZnO/CdS. It could be inferred from the evidence that the ZnO NAs/G/CdS/electrolyte heterojunction performs effectively in the aspect of self-powered UV–visible detection.