Influence of growth time and annealing on rutile TiO2 single-crystal nanorod arrays synthesized by hydrothermal method in dye-sensitized solar cells

Vertically aligned TiO2 nanorod (NR) arrays have been grown on the fluorine doped tin oxide (FTO) substrates by hydrothermal methods and the structures were employed to fabricate the dye-sensitized solar cells (DSSCs). The charge transport properties were investigated by the current to voltage curves and the electrochemical impedance spectroscopy. It was found that DSSCs containing the as-prepared and 500 degrees C annealed TiO2 NRs exhibit different trends with the growth time (t). The DSSCs assembled with the un-sintered NR arrays showed the highest power conversion efficiency (eta) of 1.87%. When DSSCs were assembled with the sintered NR arrays, nearly 400% enhanced efficiency were obtained, and the values (eta) showed a positive correlation with t. This behavior may be attributed to the improved adhesion and electric contact between TiO2 and FTO, as well as the reduced number of recombination sites. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.