Dye - Sensitized Solar Cell Titanium Dioxide Photo - Anode Film Optimizatio

The Progress of human society is always accompanied by a huge demand for energy. Traditional fossil fuels is still the main source of energy, which toxic substances and dust produced in the process of production and utilization caused a great threat. At present, solar energy is considered as the largest reserves of clean energy with great prospects. There are many ways to take fully advantage of solar energy. The photoelectric conversion device of dye-sensitized solar cells actively supported by many researchers and research, because of the low investment cost and simple process for preparing. In the five components constructed dye-sensitized solar cells, the photoanode loads the dye and is the electron transmission channels, which impact on the light-harvesting efficiency and the electron collection efficiency of the cell. Currently, many researchers consider nanocrystalline TiO2film as photoanode, which has a large specific surface area and high dye loading. However, the defect at the contact between the particles lead to seriously electron recombination. The network consisted of nanocrystalline particles increases the electron transfer distance, which limited to photo-to-electric conversion efficiency. Various methods to modify the photoanode of DSSCs, consisted of the ordered nano-array, elements doping, surface modification and nano-composite structure have been adopted to modify photoanode, which can improvethe power conversion efficiency. Surface modification can further take fully advantage of Nanocrystalline TiO2film, reducing the TiO2surface electron recombination. HCl hydrothermal treatment and preparation of composite barrier layer were used to modify to TiO2film to improve the energy conversion efficiency of the DSSCs, the main contents are as follows:Firstly, anatase TiO2nanoparticles prepared by hydrothermal method were used to prepare the slurry with1:1weight ratio of P25. The anode of DSSCs were prepared with the slurry. In the progress of hydrochloric acid hydrothermal treatment the photoanode, the TiO2particles away from the FTO glass fastly dissolve and close to the portion of the FTO glass slowly dissolve. At the same time, recrystallization of TiO2occured. The average particle size of anatase TiO2increases. Hydrochloric acid hydrothermal treatment can reform the TiO2film structure, increase the binding force of the particale, and reduce the thickness of the film. The effects of temperature and concentration of hydrochloric acid for HCl hydrothermal treatment have been on the film property. When the concentration of hydrochloric acid was lmol·L－1, the photovoltaic properties of DSSCs was the best. Electrochemical impedance spectroscopy, UV-visible diffuse reflectance spectroscopy were used to analyze the results. It was found that the increased electron injection efficiency and decreased electron recombination were the reasons that improve the efficiency of DSSCs. The PCE of DSSCs was6.58%before the HCl hydrothermal treatment and photoelectric conversion efficiency of the DSSCs increased to7.77%after the HCl hydrothermal treatment.Secondly, the TiCl4/ZrCl4mixed solution was used to modify the TiO2porous film. The concentration of ZrCl4was higher in mixed solution, the higher Zr element content was higher in the film after treatment. The formed TiO2/ZrO2barrier layer on the surface of TiO2porous film helps to reduce electron recombination and increase the apparent lifetime. The photoelectric conversion efficiency of DSSCs assemble with the photoanode TiCl4/ZrCl4mixed solution treatment increased from6.21%to7.37%.Finally, the TiCl4/Sm(NO3)3mixed solution was used to modify the TiO2porous film. The formed TiO2/Sm2O3barrier layer on the surface of TiO2porous film helps to reduce electron recombination and increase the apparent lifetime. The photoelectric conversion efficiency of DSSCs assemble with the photoanode TiCl4/Sm(NO3)3mixed solution treatment increased from6.59%to7.51%.