Photoresponse and AC Impedance Characterization of Electrodeposited TiO2-based Nanocomposite Films for Dye-sensitized Solar Cells

The effect of calcination temperature on the photoelectrochemical properties of the electrodeposited TiO2 and TiO2/SiO2 films as well as the corresponding dye-sensitized solar cells (DSSCs) was investigated in combination with photoresponse and AC impedance measurement. The thermal treatment of as-prepared electrodeposited TiO2-based films was found to decrease the charge transfer resistances at the TiO2-based film/FTO-coated glass and the TiO2-based film/electrolyte interfaces. Meanwhile, such the treatment could significantly increase the charge storage in the TiO2/SiO2 film, which is ascribed to the increase in the bonding between TiO2 nanoparticles as well as the enhancement of the bonding between TiO2 and SiO2 that effectively forms the energy barrier between the TiO2 matrix and redox electrolyte. This barrier consequently brings about the improvement of photocurrent density of the derived TiO2/SiO2 film and the photovoltaic performance of corresponding DSSC.