Surface treatment of dye-sensitized solar cell using dielectric barrier discharge

We have developed surface treatment of dye-sensitized solar cell (DSSC) using dielectric barrier discharge (DBD). The DSSC consists of TiO$_2$ nanoporous photoelectrode sensitized with dye. The photoelectrode is a 10-$\mu$m thick film made by sintering TiO$_2$ paste on a conductive glass substrate at 450 C. After the sintering, the TiO$_2$ film is dipped into dye solution for sensitization. The DBD treatment is applied to the TiO$_2$ film after the sintering. The DBD treatment improves the energy conversion efficiency, $\eta$, by a factor of 1.05 to 1.15 depending on humidity and O$_2$ concentration. It can be deduced that radicals such as O, O$_3$, and OH contribute to the DBD treatment. The DBD treatment also has an effect of reducing the sintering temperature of TiO$_2$ paste. If the TiO$_2$ paste is sintered at much lower than 450 C (i.e. $\le 300$ C), a solar cell cannot be produced, that is, $\eta = 0\%$. However, if the DBD treatment is applied after the low temperature sintering, a solar cell can be produced. This is important because the low-temperature sintering enables us to use materials that cannot resist high temperature. The DBD treatment is also applied to a plastic substrate DSSC. But the DBD causes damage on the TiO$_2$ film and at present it is not suceeded.