Nb2O5-Based Composite Electrodes for Dye-Sensitized Solar Cells.

Various semiconducting oxides are examined as alternative electrode materials for dye-sensitized solar cells. It was confirmed that Nb2O5-based electrodes exhibit a higher open-circuit voltage and fill factor, compared to TiO2-based electrodes. It was also found that a mixing of oxides, with a higher flat-band potential level such as SrTiO3, Ta2O5, and ZrO2, with Nb2O5 led to a higher open-circuit voltage. By mixing Nb2O5 with TiO2 in different ratios, it was revealed that these oxides form no chemical reaction products after a low-temperature heat treatment and a highest power output of the cells with the composite electrodes was obtained at Nb2O5:TiO2=8:2 in mass. The power output with this composite electrode was higher than that with pure Nb2O5 or with pure TiO2. The Nb2O5-TiO2 composite electrode, in which the Nb2O5 particles are dispersed on the TiO2 surfaces, exhibits high photoelectrochemical performance.