Fabrication of morphology controllable rutile TiO2 nanowire arrays by solvothermal route for dye-sensitized solar cells

Highly ordered, vertically oriented TiO2 nanowire arrays (TNAs) are synthesized directly on transparent conducting substrate by solvothermal procedure without any template. The X-ray diffraction (XRD) pattern shows that TiO2 array is in rutile phase growing along the (0 0 2) direction. The field-emission scanning electron microscopy (FE-SEM) images of the samples indicate that the TiO2 array surface morphology and orientation are highly dependent on the synthesis conditions. In a typical condition of solvothermal at 180 deg. C for 2 h, the TNAs are composed of nanowires 10 ± 2 nm in width, and several nanowires bunch together to form a larger secondary structure of 60 ± 10 nm wide. Dye-sensitized solar cell (DSSC) assembled with the TNAs grown on the FTO glass as photoanode under illumination of simulated AM 1.5G solar light (100 mW cm-2) achieves an overall photoelectric conversion efficiency of 1.64%.