Core−Shell Nanoporous Electrode for Dye Sensitized Solar Cells: the Effect of the SrTiO3 Shell on the Electronic Properties of the TiO2 Core

A nanoporous TiO 2 electrode coated with a thin SrTiO 3 layer was synthesized for photoelectrochemical applications. Introduction of this core−shell electrode to a dye sensitized solar cell increased the open circuit photovoltage while reducing the short circuit photocurrent in comparison with a cell containing the standard noncoated TiO 2 electrode. The photovoltage increases is more significant than the photocurrent reduction resulting in a 15% improvement of the overall conversion efficiency of the solar cell. The performance of the TiO 2 −SrTiO 3 core−shell electrode in the dye sensitized solar cell was analyzed by several methods including photocurrent−voltage correlation, spectro-electrochemistry, dark current measurement, IPCE, and photovoltage spectroscopy. The results indicate that the SrTiO 3 layer shifts the conduction band of the TiO 2 in the negative direction rather than forming energy barrier at the TiO 2 /electrolyte interface as found for similar coating by other materials. The shift of the TiO 2 bands is attributed to a surface dipole that is induced by the SrTiO 3 coating.