Polyol Synthesis of Zinc Oxide-Graphene Composites: Enhanced Dye-Sensitized Solar Cell Efficiency

Background: We report on the fabrication and characterization of Zinc Oxide (ZnO) and Zinc Oxide Graphene (ZnO-G) composites via a simple chemical route-polyol process, using zinc nitrate hexahydrate, ethylene glycol and reduced graphene oxide (RGO) as the precursors. The ZnO-G composites exhibit significantly enhanced photoluminescence, which is ~ 8 times stronger than that of ZnO samples. Such improved optical property is attributed to the contribution of plasmonic effect of graphene in ZnO-G. Moreover, the high crystalline quality ZnO-G composites hold great potential for dyesensitized solar cell (DSSC) applications. Method: Graphite oxide (GO) was synthesized using modified hummers method. RGO was then synthesized from GO by using hydrazine hydrate as a reducing agent. Results: The short-circuit current density was increased in the ZnOG solar cell compared to that of bare ZnO device, which is around 1.930 mA/cm2 and 0.308 mA/cm2 respectively. The conversion efficiency of the ZnO-G DSSC was measured as 0.438%, which is ~ 7 times higher than that of ZnO DSSC. The enhanced conversion efficiency achieved in ZnO-G DSSC resulted from the enhanced absorption and large surface area of the composite compared to ZnO. The synthesized flakes like ZnO and ZnO-G composites offer promising materials for DSSC applications.