Preparation Of TiO₂ Nanopowders And Its Application In Dye-sensitized Solar Cells

Dye-sensitized solar cells (DSC) have attracted more attention due to low-cost and simple technique recently. Nowadays, the efficiency of photoelectric conversion is still far lower than the theoretical value of DSC. As the anode, the properties of TiO₂ films have great influence on the photoelectric conversion efficiency of DSC. In this study, TiO₂ nanopowders were prepared by simple operation and low cost non-hydrolytic sol-gel and solvothermal synthesis. Then controlled preparation of TiO₂ nanopowders and the effect of TiO₂ anode films on the photoelectric properties of DSC were studied. The main work and results are as following:(1) TiO₂ nanoparticles and microspheres were prepared via non-hydrolytic sol-gel method. Anatase TiO₂ nanocrystalline particles with diameters of about 30～80nm were obtained with ethanol as oxygen donor. Anatase TiO₂ nanoparticles were obtained when the range of temperature from 80℃to 600℃. Mixed phase of anatase and rutile TiO₂ microspheres were synthesized by the same condition as above except that the introduction of 2.06M HCl, the size of TiO₂ spheres are up to 2μm.When isopropanol as oxygen donor, anatase TiO₂ microspheres were obtained with size of 300nm.(2) TiO₂ nanopowders were prepared via solvothermal synthesis on the basis of the process optimization parameters of the non-hydrolytic sol-gel. The sizes of anatase TiO₂ nanoparticles in the range of 30～100nm were effectively controlled via solvothermal synthesis. Mixed phase of anatase and rutile TiO₂ microspheres in a wide range of 100nm～4μm with 1-butanol as solvent. Rutile TiO₂ microflowers assembled by 1²Î¼m nanorods were synthesized via introducing 0.115M sodium lauryl benzenesulfate (DBS).(3) When the TiO₂ film prepared with 30nm nanoparticles were sintedred at 450℃and the thickness of TiO₂ film was 9μm, the properties of the solar cell was optimal: the short-circuit photocurrent was 14.72mA/cm², the open-circuit photovoltage was 0.804V, the fill factor was 0.649 and the efficiency was 7.68%. The properties of the solar cell with 300nm TiO₂ microspheres were a little lower than that with nanoparticles. The short-circuit photocurrent was 13.18mA/cm², the open-circuit photovoltage of 0.75V, the fill factor of 0.75 and the efficiency is 7.38%.(4) First 30nm TiO₂ nanoparticles prepared by non-hydrolytic sol-gel, then the TiO₂ film prepared with TiO₂ nanopowders were sintedred at 600℃, the photoelectric conversion rate of the solar cell is 6.25%. The electron lifetime of this solar cell was 10ms, which is higher than 9.4ms of that sintered at 450℃.(5) A composite film structures with the 30nm particles as the bottom and 2μm microspheres as the upper was designed. The solar cell prepared with this composite film generated the short-circuit photocurrent of 10.26 mA/cm², the open-circuit photovoltage of 0.72V, the fill factor of 0.7 and the efficiency is 5.19%.And the electron lifetime of this solar cell was 10.8ms.