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.