Nano-porous TiO₂ layer using ultrafine nano-particles for the blocking layer in dye-sensitized solar cells

A nano-porous TiO₂ layer was produced by spray-deposition using ultrafine anatase nano-particles for the blocking layer for the dye-sensitized solar cells (DSCs). The microstructure and the electrochemical properties of the spray-deposited TiO₂ layer were examined. The results of electrochemical properties showed that the spray-deposited TiO₂ layer was capable to suppress the I- ₃ ions diffusion to FTO substrate, reducing the electron recombination between the electrons on FTO substrate and I-₃ ions in electrolyte. In addition, the connection between TiO ₂ film and FTO substrate was improved by the TiO₂ layer. Therefore, the short circuit current density and thereby the phototo-electric energy conversion efficiency were improved by this blocking layer. The blocking effect of the porous layer was attributed to both the complicated pore structure of the spray-deposited layer and the enhanced connections between TiO ₂ film and FTO substrate. The low temperature characteristic of spray deposition approach indicates that it is suitable to the flexible-based DSCs.