Quality inspection of Titanium-dioxide blocking layers for efficient Dye sensitized solar cells photoanode

Dye sensitized solar cells are prospective devices for the usage as additional energy sources, since their fabrication is simple, they are low cost and they have low impact on the environment. One of the main parts of these cells is photoanode, which converts sunlight into electricity. The process that has the negative influence on the photoanode efficiency is the process of recombination. The role of the blocking layer is to prevent this process. In dye sensitized solar cells, blocking layer are usually made of titanium dioxide, TiO
2
. There are many methods of deposition of the blocking TiO
2
layer on the substrate. In this work we examined dip-coating technique, which is widely used in the literature. The samples were prepared under different conditions, in order to find the best parameters for efficient blocking of recombination. Afterwards, the samples were investigated with the electrochemical impedance spectroscopy for inspection of the surface coverage and charge transfer through the layers. Also, the transparency of the deposited layer was examined by UV-VIS. The best results are obtained with the samples that were dip-coated in a 40 mmol water solution of TiCl
4
and treated in a water bath for 30 minutes, at 70 °C. In future work, solar cells which will differ only in the blocking layers will be fabricated, in order to see if there is a correlation between the cell’s efficiency and the results obtained in this work. As a result, validation of the electrochemical impedance spectroscopy as a method for photoanode quality inspection will be achieved.