Ultra-long hierarchical bud-like branched TiO2 nanowire arrays for dye-sensitized solar cells

The ultra-long hierarchical bud-like branched TiO2 nanowire arrays on fluorine-doped tin oxide glass substrate have been prepared via a two-step solution route, which involves the growth of the anatase TiO2 nanowires with the length of 48 μm on fluorine-doped tin oxide glass substrate, followed by a secondary growth of the rutile TiO2 nanorods on the as-grown TiO2 nanowires backbone. The dye-sensitized solar cell based on the hierarchical bud-like branched TiO2 nanowire arrays shows a power conversion efficiency of 6.00%, which is nearly 2.88 times as high as that of bare TiO2 nanowire arrays because of the preferable nanostructure, which not only retains the efficient charge separation and transport properties of one-dimensional TiO2 nanostructures, but also improves the amount of dye adsorption and light-scattering ability due to the branched structure.