Control of titania layer of Dye-Sensitized Solar Cell (DSC)

In recent days, green technology that is based on solar cell is highly focused for sustainable society. So, the efficiency of Si type of solar cell is drastically improved. On the other hand, dye-sensitized solar cell (DSC) is also highly focused because of flexibility and design in spite of low efficiency. To clear the low efficiency problem, many studies on the development of dye and titania were carried out. Because the dye was developed, then the absorbed wavelength became broad and the absorption ratio on each wavelength was increased. Due to the study on titania, unique shapes of titania were suggested and the absorption characteristics were improved. In spite that many studies on chemical view were carried out, few studies on fabrication process were carried out. So, we focused on fabrication of titania layer of DSC. Usually, the titania layer was fabricated by the doctor blade method or the screen print method. The inside of the fabricated titania layer utilizing the ordinary method had little porous. In the case that the porous titania layer was formed, then the flow of electricity was increased due to the increased surface of titania layer. We applied the electrostatic inkjet method for fabrication of the titania layer because the porous layer was formed due to evaporation effect utilizing the electrostatice inkjet method. We already formed porous titania layer and achieved the efficiency improvement. In this paper, we investigated the fundamental characteristics on fabrication of porous titania layer utilizing the evaporation effect. The experimental set-up to investigate the characteristics was shown as follows. Titania paste was filled with the ink tank. Nozzle was installed at the end of the tank. FTO glass electrode was set on the XY linear stage and the rotation stage. When the high voltage was applied between the nozzle and the glass electrode, small droplets were ejected because the electrostatic inkjet method was took place. Formation and ejection of the small droplets were observed with a high-speed camera and a light. The evaluation of the porous titania layer was carried out with the SEM and XRR. We investigated the characteristics of the porous titania layer in case that the rotation speed was changed.