Influence of Interface Structure on the Properties of ZnO/Graphene Composites: A Theoretical Study by Density Functional Theory Calculations

The structures as well as electronic and optical properties of the ZnO/graphene composites were theoretically studied by density functional theory calculations. Graphene was composited on monolayer and bilyer ZnO as well as wurtzite ZnO thick slab (0001) surface with zinc and oxygen terminated. We calculated and analyzed the binding energies, difference charge densities, PDOSs, work functions, and optical properties of the composites. It was found that the electronic properties of graphene were retained when graphene combined with ZnO layers. Graphene on the ZnO thick slab (0001) surface with zinc terminated shows obvious electronic doping and enhanced work function. On the contrary, graphene on the ZnO thick slab (0001) surface with oxygen terminated suggested hole doping and decreased work function. The optical properties were also tunable by changing interface structure.