Photovoltaic Performance of Vertically Grown ZnO nanorods in Dye-sensitized Solar Cells

For an application to the photoelectrode in dye-sensitized solar cells (DSSCs), we fabricated ZnO nanorod arrays on fluorine-doped tin oxide (FTO) coated glass substrate by chemical bath deposition, and modified its surface through sodium silicate coating. Effects of the surface modification on the morphology of ZnO nanorod arrays, as well as the photoelectric conversion properties in DSSCs were investigated. From the field-emission scanning electron microscopy (FE-SEM) images, ZnO nanorods are observed to be vertically grown on FTO substrate. The surface treatment via dip coating within sodium silicate solution gives rise to increase the photocurrent, resulting in the increase of solar-to-electrical power conversion efficiency. This may be originated from that the surface-treated ZnO photoelectrode has higher conduction edge to introduce an energy barrier for increasing charge separation and suppressing recombination rate at the photoelectrode-electrolyte interface.