Enhanced performance of the dye-sensitized solar cells by the introduction of graphene oxide into the TiO₂ photoanode

In order to enhance the performance of the dye-sensitized solar cells (DSSCs), graphene oxide (GO) was introduced into the TiO₂ photoanode to construct a GO-TiO₂ composited photoanode. The photoelectric properties of the as-constructed photoanode were studied in comparison with those of the TiO₂ photoanode and the effect of GO obtained by different methods on the performance of the GO-TiO₂ composited photoanode was also compared. After constructed with GO, the photoanode displayed enhanced light and dye adsorption properties with a higher light harvesting efficiency, lower internal resistances, a faster electron transport, and a lower charge recombination rate, which resulted in a higher current density. At the optimal condition, the DSSCs based on the photoanode modified by GO obtained in our laboratory (GO1) exhibited a J_sc of 18.16 mA cm^-2, a V_oc of 0.68 V, and a FF of 0.59 with a energy conversion efficiency (η) of 7.30%, indicating an increased performance compared with that of the DSSCs based only on the pure TiO₂ photoanode, which had a J_sc of 14.41 mA cm^-2, a V_oc of 0.66 V, and a FF of 0.60 with a η value of 5.67%. However, when GO that obtained from a production line in a factory (GO2) was used, the performance of the DSSCs was further improved, which showed a J_sc of 19.49 mA cm^-2, a V_oc of 0.68 V, and an FF of 0.59 with a η value of 7.83%. Different performances between GOs that obtained from the laboratory and the factory were mainly attributed to their distinct production processes, which distinguished their properties from each other. It is a potential method to enhance the performance of the DSSCs by constructing a GO-TiO₂ photoanode with a suitable quality GO.