Preparation of rGO/ZnO photoanodes and their DSSCs performance

Abstract In this study, we report a mild and controllable preparation method for graphene oxide (GO) and ZnO ultrafine powder, respectively. On this basis, reduced graphene oxide (rGO)/ZnO composite powder for the photoanodes of dye-sensitized solar cells (DSSCs) was synthesized by chemical reduction method. Phase composition, microstructure, chemical structure, conductivity, and specific surface area were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman, and Brunauer-Emmett-Teller (BET) method, respectively. Photoelectric performance of DSSCs was studied by the current density-voltage (J-V), electrochemical impedance spectra (EIS) photoelectric test system. As rGO possesses higher adsorption capacity and excellent conductivity, hence it may effectively promote separation of electrons and holes, transmission ability of electrons and holes, and utilization of the light. By contrast, the as-synthesized zinc oxide (ZnO) may increase adsorption capacity of dye molecules, so photoelectric conversion efficiency (PCE) of the solar cells is increased by means of synergistic effects. When adding rGO in the rGO/ZnO composite powder at 1.25 wt%, PCE reaches to 6.27%, an increase of 20.6% more than that of pure ZnO as the photoanode.