Application Of Urchin-like TiO₂ Microspheres And Their Composites Modified By Gold Nanoparticles In Dye-sensitized Solar Cells

Dye-sensitized solar cells?DSSCs?,as typical representatives of the third-generation solar cells,have attracted much attention due to their low cost,environmental friendliness,and simple process.The photoanode is an important part of DSSCs and will greatly affect the performance of the DSSCs.Although the DSSCs based on TiO₂ nanocrystalline thin films have achieved a certain photoelectric conversion efficiency?PCE?,the simple TiO₂ nanocrystalline thin films have the disadvantages of low light scattering ability and large carrier recombination.Therefore,three-dimensional hierarchical TiO₂ structures were prepared to replace TiO₂nanocrystals to improve the light scattering ability of photoanode films and reduce carrier recombination,thereby significantly improving the performance of DSSCs.In this paper,urchin-like TiO₂ hierarchical microspheres?UTHMs?with a specific surface area of 331 m² g^-1 were synthesized by a simple one-step hydrothermal method.The morphology,crystalline phase and specific surface area of the synthesized microspheres were characterized by SEM,TEM,XRD and BET.Further,UTHMs were applied to the photoanodes of DSSCs.DSSCs were assembled,and characterization tests such as photovoltaic characteristics?J-V?,spectral response characteristics?IPCE?,and the amount of dye loading were performed.It is shown that UTHMs can significantly improve the loading of the dye on the photoanode and the scattering ability of the photoanode.Compared with DSSCs based on TiO₂ nanocrystalline film,the efficiency of DSSCs based on UTHMs film is improved by 17.5%.In order to further improve the performance of DSSCs,noble metal gold?Au?nanoparticles were adsorbed on the surface of UTHMs to synthesize Au nanoparticle-decorated urchin-like TiO₂ hierarchical composite microspheres?Au-UTHMs?.The localized surface plasmon resonance?LSPR?of the noble metal is used to enhance the light absorption of the photoanode.We prepared composite photoanode films by combining Au-UTHMs with UTHMs in a series of different ratios.By characterization test of J-V and IPCE of the DSSCs,it was found that when the mixing ratio of Au-UTHMs/UTHMs was 2wt%,the DSSCs achieved the best PCE?7.21%?.Compared to UTHMs-based DSSCs?6.10%?,the PCE is increased by 18%.