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.