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

Abstract

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.