Research Of Photoanode In Dye-Sensitized Solar Cells (DSSC)

In order to improve the cost-effective of dye-sensitized solar cells, every part of photoanode electrodes, including transparent conducting glasses, porous TiO₂ thin film, scatting layers, were chosen as our research object in this paper. We utilized the technique of doctor-blade to prepare porous TiO₂ film, then dipped it into dye solution for 24 hours, after that, the electrolyte was immersed into TiO₂ film, at last, we assembled dye-covered TiO₂ electrode and Pt-counter electrode into a DSSC. The performances of photoanode electrodes were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), UV-visible spectrophotometer, and transmission electron microscopy (TEM), the photovoltaic performances of dye-sensitized solar cell (DSSC) were measured under AM1.5 illumination and dark conditions, respectively. The conclusions are revealed as follows:The first, blocking layer thin films consisted of TiO₂ particles were prepared on a conductive fluorine-doped tin oxide (FTO) substrate by hydrolysis of TiCl 4 solution with different concentrations, Increasing in the concentration of TiCl4 solution leads to an increase in the blocking layer thickness as well as variation of its morphology; the blocking layers prepared by TiCl 4 solution of 0.04 mol/L can suppress the dark current most efficiently and give rise to the highest power conversion efficiency of 7.84% under AM1.5 illumination conditions.The second, the surface of IWO thin films is smoother than FTO's, when dipped into electrolyte, its surface morphology can't be affected; the sheet resistance of IWO thin films becomes larger after annealing in the air; the transmittance of FTO is better than the one of IWO in visible region, we use FTO and IWO as the substrate of DSSC, it is revealed that the current density, photo- voltage, fill factor and conversion efficiency of DSSC composed of FTO are higher than the ones of IWO. The third, The scattering layers, composed of 200 nm and 400 nm TiO₂ particles, can enhance the reflectance, absorbance of sunlight in porous titanium dioxide thin films, and the haze of them, the photovoltaic performances of the DSSC containing 200nm TiO₂ particles are better than that containing 400nm TiO₂ particles.The fourth, the dispersion of titanium dioxide particles will be improved, the amount of adsorbed dye molecules is increased, there will be changes in the surface states, when they are treated with hydrochloric acid and nitric acid, separately. The short current density and power conversion efficiency of DSSC composed of these treated particles are inhanced, in addition, it is proved that HCl-treated DSSC is superior to that of the HNO₃-treated one.