Improvement of light-harvesting efficiency of TiO₂ granules through chemical interconnection of nanoparticles by adding TEOT to spray solution

Mesoporous TiO₂ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. TiO₂ granules obtained showed about 400 nm in size, the specific surface area of 74-77 m²/g, and average pore size of 13-17 nm. The chemical modification of TiO2 granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (η=6.72%) was enhanced about 14% higher than primitive nanoparticles.