Rare Ions Doped TiO₂ Nanomaterials And Applied In Dye-sensitized Solar Cells

TiO₂ semiconductor was considered to be a photoelectrode material that possesses extra potential due to its wide band and light resistance.Doping with metal ions and nonmetal element have shown mixed effects,which reduced the bandgap of TiO₂ to some extent and served mainly as recombination centers for electrons and holes,counteracting their positive effects.If the ultraviolet irradiation can be transferred to visible light by an down conversion luminescence process,more solar irradiation can be utilized,and the photocurrent of the dye-sensitized solar cell?DDSC?will be effectively enhanced.The rare earth ions were introduced into the photoanode in the DSSC to improve the light use ratio,photocurrent and photovoltaic conversion efficiency.The main results were as follows:1)Samarium ions?Sm3+?-doped TiO₂ photoelectrodes are used to enhance the photovoltaic efficiency of DSSC.The improvments are especially exhibited in the visible light absorption,interface area and photocurrent density Jsc.In comparison to different doping concentrations,optimized 0.05 g-Sm/TiO₂ could achieve fill factor of 0.69 and efficiency of 7.23%.It is obviously better than the undoped-titania photoelectrodes.This enhancement is due to the improved UV radiation harvesting via a down-conversion luminescence process by the doped samarium ions and enhance the dye adsorption.2)Down-conversion luminescence layer of La3+-doped TiO₂ was prepared by hydrothermal-sintering process,and then assembled in a DSSC.The structure,optical and photoluminescence properties of down-converting photoelectrode with the La/TiO₂ were characterized by XRD,SEM,EDX and so on.The photoelectric conversion efficiency of dye-sensitized solar cell?DSSC?fabricated with 0.05 g-La/TiO₂ reached 7.02%,which gave an efficiency improved by 10.36% compared with that of cells fabricated from pure TiO₂.The improvement in efficiency was ascribed to more dyes adsorbed on the surface of TiO₂ and increase the absorption of light.3)Down-conversion luminescence layer of Ce3+-doped TiO₂ was prepared by hydrothermal-sintering process,and then assembled in a DSSC.Various techniques such as XRD,SEM and EDX were used to characterize the products and J-V,EIS,UV-vis were used characterize the electrochemical properties.When 0.05 g-Sm/TiO₂ could achieve the best photoelectric conversion.4)Down-conversion luminescence layer of Sm3+-doped mesoporous TiO₂ was prepared by hydrothermal-ultrasound process,and then assembled in a DSSC.The higher specific surface area of the Sm3+-doped TiO₂ photoanode leading to a greater amount of dye adsorption,Sm has special properties for better inner connection for the transportation of electron.A 2.48 mA/cm2 enhancement of short-circuit current density and 26.56% improvement of the overall efficiency at1.5%-Sm/TiO₂ were achieved,relative to that of a cell containing non-doped TiO₂ under the same condition.5)Down-conversion luminescence layer of Y3+-doped mesoporous TiO₂ was prepared by hydrothermal-ultrasound process.Various techniques such as XRD,SEM and BET were used to characterize the products.After analysis the physical properties that the mesoporous microspheres Y/TiO₂ suitable for the DSSC photoanode.