Synthesis of long TiO2 nanowire arrays with high surface areas via synergistic assembly route for highly efficient dye-sensitized solar cells

Vertically aligned single crystal TiO2 nanowire arrays grown on transparent conductive substrates are of considerable interest for use as photoanodes in dye-sensitized solar cells because they can provide direct pathways that ensure the rapid collection of charge carriers generated throughout the cells. However, growth of TiO2 nanowire arrays on conductive glass with the combined characteristics of a large surface area and lengths up to tens of micrometers is still challenging and desirable for highly efficient solar cells. Here, we reported a mild hydrothermal approach for growing vertically aligned TiO2 nanowire arrays directly on conductive glass via the synergistic interaction of the octanoic acid and titanium trichloride. The resulting single crystal TiO2 nanowire arrays possess a large surface area of 95 m2 g−1 and a controlled length in the range of 6–46 μm. By applying 9.6 μm-long nanowire arrays in dye-sensitized solar cells, an overall photoconversion efficiency of 5.13% is achieved under a white light illumination of 100 mW cm−2.