Performance improvement of dye-sensitized solar cells using room-temperature-synthesized hierarchical TiO2 honeycomb nanostructures.

Highly ordered hierarchical TiO2 nanostructures involving primary honeycomb and secondary nanoparticles and nanowires are prepared by a two-step facile process. The TiO2 nanotube arrays grow first on Ti foil through anodization. After the wet-chemical reaction of the TiO2 nanotube arrays with alkaline and acid solution in turn, the hierarchical nanostructures wire-in-honeycomb and porous honeycomb are obtained by a dissolution-coagulation and dissolution-adsorption mechanism, respectively. The power conversion efficiency of the hierarchical TiO2 honeycomb nanostructures for the dye-sensitized solar cells (DSCs) shows a significant improvement, as high as 5.73%, increased by 1.42 times compared with that of TiO2 nanotube arrays. The performance improvement of DSCs based on the hierarchical nanostructures is attributed to the increase in the specific surface area.