Fabrication of Electron Passes in Nano-TiO 2 Layer by High-Velocity Oxy-Fuel Method for Dye-Sensitized Solar Cells

Necking among titania nanoparticles in porous titania layers of dye-sensitized solar cells (DSC) was carried out by the collision of nanoparticles in a very fast gas flow of more than 1000–1500 m/s. where the substrate was held in an ambient atmosphere. The rapid gas flow was obtained by a high velocity oxy-fuel method (HVOF) operated at an intermediate temperature. The photovoltaic performance of a cell prepared by the HVOF method was slightly lower than that of DSCs fabricated by a conventional method involving coating-baking processes. The slightly low efficiency was explained by the small dye load and slightly lower electron diffusion coefficient in a porous titania layer. The time needed for fabricating a nanoporous titania layer (10 ×10 cm 2 ) by the HVOF method was only a few minutes and was extremely shortened from the 2 h needed in the case of conventional coating and heating processes, which demonstrates that the HVOF method is useful for necking titania nanoparticles within an extremely short time.