Enhancement of Photocurrent and Photovoltage of Dye-Sensitized Solar Cells with TiO₂ Film Deposited on Indium Zinc Oxide Substrate

The effects of using indium zinc oxide (IZO) as a conducting substrate in dye-sensitized TiO₂ solar cells (DSC) on their photocurrent-voltage characteristics are studied. We have found that both short-circuit photocurrent (J_sc) and open-circuit voltage (V_oc) of IZO-based cells are substantially improved by about 40% and 10%, respectively, when compared with those of cells based on fluoride-doped tin oxide (FTO). The J_sc increase is correlated to the improved contact between IZO and TiO₂ and enriched conduction band electrons in the TiO₂-on-IZO electrode, due to the blocking of surface states by the evaporated metallic components of the substrate. The combined effects of the negative shift of flat band potential and the reduction in recombination explain the V_oc increase. Our experimental finding suggests that IZO-coated substrate makes more efficient DSC than a FTO-coated one.