Self-powered ultraviolet photovoltaic photodetector based on graphene/ZnO heterostructure.

• Surface treatment was conducted by soaking ZnO film into H 2 O 2 solution. • The contact between graphene and ZnO was transformed from ohmic to Schottky. • Graphene/H-ZnO PD exhibits a fast photovoltaic response to UV light at zero bias. • The fast response speed benefits from pyro-phototronic effect and built-in field. Compared to ZnO-based photoconductive photodetectors (PDs), photovoltaic PDs possess the advantages of easy fabrication, low dark current, high response speed and possible self-driven ability. In this paper, an ultraviolet (UV) photovoltaic photodetector based on graphene/ZnO heterostructure was fabricated and investigated. A simple surface treatment was conducted by soaking the as-grown ZnO film in H 2 O 2 solution at room temperature. After this processing, a transition from ohmic contact to Schottky contact was observed in graphene/ZnO interface, accompanied with a high-performance photovoltaic behavior for the graphene/H 2 O 2 -treated ZnO (denoted as G/H-ZnO) heterostructure. The self-powered Schottky photodetector of G/H-ZnO exhibits a responsivity of 50 μA/W and a short rise/decay time of 32 ms at zero bias. The fast response performance benefits from the rapid separation of photogenerated carriers, which can be attributed to the synergistic effect of pyroelectric potential and built-in electric field at graphene/ZnO interface. This study provides a facile approach for the development of ZnO-based self-powered photovoltaic devices. [ABSTRACT FROM AUTHOR]