Preparation of silica-modified TiO2 and application to dye-sensitized solar cells

Silica-modified titania (Si–TiO2) was synthesized by the glycothermal method and applied for dye-sensitized solar cells (DSCs). Si–TiO2 crystallized in anatase structure and was found to be thermally stable. Crystallite size of Si–TiO2 became smaller as Si loadings in Si–TiO2 increased, and Si–TiO2 of small crystallite size adsorbed large amount of dyes on the surface. The photoelectrochemical conversion efficiency of the DSC using Si–TiO2 was influenced mainly by the electron transfer between Si–TiO2 particles. The Si–TiO2-based DSCs showed a maximum in the conversion efficiencies when the crystallite size of Si–TiO2 was around 15 nm, irrespective of the Si loadings. To improve the connectivity between Si–TiO2 particles, Si–TiO2 particles were mixed with TiO2 sol, which was synthesized by the hydrothermal method. Dye-sensitized solar cells prepared using these pastes were able to reduce the influence of the resistance between the particles and improved their conversion efficiencies stemming from the increase of short circuit currents, since Si–TiO2 could adsorb large amount of dyes.