Dye-sensitized Solar Cells Based On Hyperbranched TiO₂ Nanowire Films And Their Photoelectric Properties

The fossil fuels such as oil,natural gas and coal are the main sources of energy used all over the world.With the development of economy in our country,the demand for energy is increasing.Moreover,the burning of the fossil fuels emits ton of carbon dioxide that pollute the environment and cause much problem.As a clean and renewable energy,solar energy attracts more and more attention.Dye sensitized solar cells have become the focus of research because of their simple process,cheap raw materials and high theoretical efficiency.As the anode of dye-sensitized solar cells,TiO₂ nanocrystals films are not conducive to electron transport because of their large grain boundaries.TiO₂ nanowire films can reduce the electron recombination with the direct electron transport channel.In this experiment,hyperbranched TiO₂ Nanowire Films were prepared by solvothermal method on FTO conductive substrates and applied to the dye-sensitized photoanode of solar cells.The effects of seed liquid concentration,reaction temperature and reaction time on the growth of hyperbranched TiO₂ nanowire films were investigated,and the growth mechanism of hyperbranched nanowires was discussed.Furthermore,the TiO₂ nanowire films were assembled into batteries,and the influence of the films prepared under different conditions on the photoelectric performance of the devices was investigated.The transparent conductive substrate FTO was pretreated with different concentration of seed liquid.Then,the sample annealed at 550 �C for 1 h in air.When the concentration of the TiCl₄ precursor solution was 0.2 mol/L.We could get dense and vertical TiO₂ nanowire.And the DSSC prepared with this condition has the highest photoelectric conversion efficiency of 6.89%.The experiment used TiCl₄ precursor solution to pre-treat FTO with the concentration of 0.2 mol/L.Then,The experience used titanium potassium oxalate as reactant,deionized water and diethylene glycol as solvent,and explored the growth mechanism of the hyperbranched TiO₂ nanowire arrays by controlling the temperature and time.The results showed that in the initial stage of the reaction,with raising temperature and time,the growth of nanowires showed a layered structure.The best temperature is 180 �C,the suitable reaction time is 9 h.And the thickness of film is 7.5 ?m.For gettig higher specific surface area of films,total number of Ti sources in the reaction solution increased by keeping the solution concentration constant and increasing total volume.It found that the film thickness increases to 9.5 ?m.When The reactants contained 0.6 g titanium potassium oxalate,15 mL deionized water as solvent 45 mL diethylene glycol.The photoelectric conversion efficiency of the solar device made by the photoanode is up to 7.41%.