Efficiency improvement of dye-sensitized solar cells based on electrodeposited TiO2 films by low temperature post-treatment

Porous crystalline TiO2 films can be prepared at low temperatures (80 °C) by surfactant-assisted electrodeposition from TiCl3 solution. Nevertheless, up to now calcination at high temperatures (typically 450 °C) was still necessary to establish a good performance of these films in dye-sensitized solar cells (DSSC). With this study we report that water vapour treatment at much lower temperatures (150 °C) for 1 week improves the performance of the films in DSSC to the same degree as calcination although the overall crystallinity remains lower. Reason for the good efficiency is that the porous structure stays intact and thus the dye molecules can be better adsorbed. Avoiding high temperatures during the preparation process of TiO2 films for the application in DSSC enables the use of polymer substrates for the fabrication of flexible solar cells.