Plasmonic Enhancement of the Performance of Dye-sensitized Solar Cells by Incorporating Hierarchical TiO2 Spheres Decorated with Au Nanoparticles

Hierarchical TiO2 spheres (HTS) containing needle-like nanorods and decorated with Au nanoparticles are synthesized, forming the HTS-Au microspheres. These microspheres are hybridized into TiO2 nanocrystalline film to act as a scattering body on top of a pure TiO2 nanocrystalline layer, forming a novel composite photoanode. The effects of such HTS-Au microspheres on the performance of the photoanode and dye-sensitized solar cell (DSSC) are studied. Study reveals that both light absorption and scattering in the photoanode are greatly enhanced, leading to the significant increases of the short-circuit current density (Jsc) and photoelectric conversion efficiency (η) of the DSSC. The optimal HTS-Au-based DSSC exhibits the maximum Jsc of 14.56 ± 0.20 mA cm−2 and η of 7.37 ± 0.05%, markedly higher than those of the pure TiO2-NPs-based DSSC by 23.4% and 23.0%, respectively. The great improvements in the properties of the optimal HTS-Au-based DSSC can be mainly attributed to these factors: the heightened light absorption owing to the localized surface plasmon resonance from Au nanoparticles, the higher light scattering ability by the HTS microspheres, and the possible faster electron transfer channel provided by the needle-like nanorods. These different functions play important complementary roles in enhancing the light harvesting, the Jsc and η of the DSSC.