Optimization of the TiO2 layer in DSSCs by a nonionic surfactant

Developing dye-sensitized solar cells (DSSCs) further is of utmost importance in a time of increasing energy consumption and the necessity to change to renewable energy sources. Opposite to silicon-based solar cells, DSSCs can be produced from low-cost, non-toxic materials. In addition, they can be applied on flexible substrates, enabling even utilization on textile architecture. On the other hand, reaching efficiencies in a similar order of magnitude as with silicon-based solar cells is only possible by highly pure and toxic materials. This is why optimization of DSSCs with non-toxic and affordable materials is of high interest. Here we report on the possibility to increase the TiO2 layer performance by adding a nonionic surfactant, focusing on a non-toxic electrolyte and a natural dye. Our results show that coating the semiconducting layer from a solvent including a surfactant increases the efficiency of the DSSC. To enable comparison with results of other groups which are often reported for very small active areas, we compare three different areas between 0.25 cm(2) and 6.0 cm(2) and show that the efficiencies are more than doubled for the smallest active area in comparison to the largest one. This underlines the necessity to perform more research on large-area DSSCs, e.g. by combining several smaller cells, aiming at possible applications on tents or other large textile areas.