Direct contact between the hole transport phase and conductive substrate in DSSC causes a short circuit that significantly reduces the cell performance. It is well accepted that in order to avoid this recombination process a compact blocking layer should be deposited on the conducting substrate especially in the case of solid and quasi-solid cells. Spray pyrolysis, sputtering and chemical vapor deposition have been reported as the fabrication methods for compact layer of materials like TiO₂, TiO_x and Nb₂O₅. However, sputtering and chemical vapor deposition require relatively expensive equipment, while spray pyrolysis requires multistage processing.
We present here a new blocking material fabricated by a different method. The new blocking layer consists of the compositional oxide TiO₂-Al₂O₃. The compact layer is deposited by sol-gel electrophoretic deposition (sol-gel EPD) on the conductive substrate prior to the deposition of the nanoporous film. Consequently, by a simple one step process we were able to replace resistor like J-V curves of a solid state DSSC by ones having good fill factor and open circuit voltage. We found that blocking properties can be achieved also by sol-gel EPD onto preformed TiO₂-mesoporous layer. Using HRSEM, X-ray photoelectron spectroscopy, cyclic voltammetry and photovoltaic characteristics of both liquid electrolyte and solid hole conductors cells we optimized the composition, thickness and sol-gel EPD conditions of the new TiO₂-Al₂O₂ blocking layer. In this report we will show the simplicity, flexibility and reproducibility of the new method as well as basic studies of the blocking phenomena in these materials.