Controlled growth of vertically aligned TiO2 nanorod arrays using the improved hydrothermal method and their application to dye-sensitized solar cells

Well-aligned rutile TiO2 nanorod arrays were synthesized directly on FTO substrate by hydrothermal method. By controlling the growth parameters such as precursor concentration, acidity, growth temperature and growth time, we obtained various morphologies of nanorods. Optimization of the growth recipe leads to well-aligned vertical arrays of TiO2 nanorods with appropriate length to width ratio. Field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD) are used to characterize TiO2 nanorods. Dye-sensitized solar cell (DSSC) assembled with the optimized nanorod arrays achieves an overall photoelectric conversion efficiency of 1.86%. Electrochemical impedance spectroscopy (EIS) measurement was applied to compare the electron transport and recombination properties of DSSCs using TiO2 nanorods with different length.