Photoelectric properties of graphene oxide-ZnO composite nanosheets vertically grown on substrate

In the present work, the graphene oxide (GO) and vertically oriented ZnO nanosheets composite structures on substrate supported by the ZnO nanorods were realized. The elaborate microstructures, chemistries and relevant energy level structures of different composites were carefully characterized. By exploiting the intrinsic excitation of the semiconducting GO for photoelectric conversion, the open circuit photovoltage and the short circuit photocurrent responses of the heterojunction films under visible irradiation were investigated through photoelectrochemical measurements, with maximum of −77.0 mV and −3.8 μA/cm2, respectively. Comparisons of the conversion properties of the samples suggested two conclusions. Firstly, the substantial C-O-Zn bonds at the GO-ZnO interfaces should be key to improved photovoltaic performance, by facilitating the separation of photo-generated charge carriers. Secondly, the perpendicular ZnO nanosheets with less defects and shortened paths, and the coated GO flakes on ZnO with more ordered lattice and extensive exposure to electrolytes together have resulted in enhanced conversion performance, since they are beneficial for more fluent collection of electrons and holes, respectively. In virtue of the specific heterogeneous configuration of the composites as prepared, this work has pushed a step for the practical photovoltaic application of GO as absorbers and hole transporters.