Enhanced power conversion efficiency of dye-sensitized solar cells with multifunctional photoanodes based on a three-dimensional TiO₂ nanohelix array

Developments of metal oxide nanostructures for simultaneous improvements in light harvesting and charge collection can lead to a significant technical progress in various applications such as photoelectrodes for photoelectrochemical cells and various types of solar cells. Here we present an array of three-dimensional titanium dioxide (TiO₂) nanohelixes infiltrated with TiO₂ nanoparticles as a multifunctional photoanode for dye sensitized solar cells (DSSCs). The unique geometry and the near-single crystallinity of the vertically aligned TiO₂ nanohelix array results simultaneously in strong light scattering and enhanced carrier transport and collection, while maintaining a comparable surface area accessible for dye molecules by the infiltrated TiO₂ nanoparticles. Consequently, despite a ~40% reduction in dye loading, the overall photon conversion efficiency of the DSSC with the nanoparticle-infiltrated nanohelix-array photoanode is enhanced by 6.2% in comparison with the DSSC with the conventional nanoparticle photoanode.