Improving transparency in dye-sensitized nanostructured solar cells by optimizing nano-porous titanium dioxide photo-electrode

Today’s the technology based on dye-sensitized solar cells (DSSCs) has an important role in all photovoltaic system technologies. DSSCs can generate electricity with various degrees of transparency; this makes it suitable for use in various industries, especially in construction industry as smart windows. In fact DSSC can produce electricity and having natural light, simultaneously. It is obvious that DSSCs need to absorb solar radiation as much as possible. Since, the effective use of all incident lights leads to an increase in cell efficiency and this increase in efficiency is related to the amount of dye adsorbed on the surface of nanostructured electrode, so higher amount of dye for higher efficiency tends to the reduction of transparency of the cell. This paper has been attempted to investigate the relationship between these two parameters of transparency and efficiency for DSSCs by maintaining the cell stability in a long-term time interval. The results showed that the thickness of the nano-porous titanium dioxide film and the size of its nanoparticles have an important role as the photo-anode due to the absorption of the dye molecules in the DSSCs. Using the smallest size of TiO₂ nano-particles in the anatase phase, and optimizing the TiO₂ layer thickness by adding terpineol solvent in it, the stability of the DSSC is improved exceedingly and the level of transparency increased from 30.43 to 46.5% with maintaining the efficiency of the 3.2%. Besides, we used a new two-step method to fabricate higher performance cells and the efficiency increased to 3.78 with saving its 46.5% transparency. Results indicate that other parameters like using different electrolytes and different deposition methods of platinum counter electrode have lower effects in this optimization compared to the photo-anode effect.