Sol–gel modified TiO2 powder films for high performance dye-sensitized solar cells

Techniques in TiO2 film fabrication process are a very important aspect in construction of efficient dye-sensitized solar cells (DSSCs). Among fundamental factors in high efficiency solar cells is the development of a highly porous nanocrystalline film in a relatively thick and mechanical stable TiO2 network. In present work, two types of commercial titania powders with high loading (74% (wt.%) in the final films), Degussa P25 powders and Ishihara ST-01 powders, have been successfully incorporated into a mesoporous structured TiO2 crystalline network. The good mechanical stability of both types of films involves the presence of a titanium alkoxide solution mixed with non-ionic surfactant Tween 20 as a suitable binder precursor to immobilize commercial titania nanoparticles on a SnO2:F conductive glass via a dip coating sol–gel process. The results of photoelectrochemical characterization of the films in a dye-sensitized solar cell showed that both films presented high conversion efficiency (about 6%) with only a slight difference on their photovoltaic behavior, when a quasi-solid state electrolyte was employed. The crystalline structure of the foreign titania particles, the particle size and the existence of any agglomeration, as well as the surface area and the pore structure of these films made of different titania powder sources were examined in detail and are discussed in relation to the relatively high solar to electrical energy conversion efficiency obtained in such quasi-solid state DSSCs.