Fabrication of hierarchical ZnO nanostructures for dye-sensitized solar cells

Long ZnO nanowires and hierarchical ZnO nanostructures were fabricated by simple anodization and subsequent electrochemical deposition for use in dye-sensitized solar cells (DSSCs). The length of the long ZnO nanowires increased with increasing anodization time at a constant voltage, with a growth rate of 50–80 μm h−1. The optimal electrochemical deposition time for preparing hierarchical ZnO nanostructures on ZnO nanowires was approximately 1.5 times the anodization time. Compared to the ZnO nanowires, the hierarchical ZnO nanostructures exhibited higher power conversion efficiency due to an enlargement of the internal surface area. In addition, the hierarchical ZnO nanostructures showed good corrosion resistance in an acidic dye solution.