Dye-Sensitized Solar Cells Based On Ordered TiO2 Nanotube Arrays On Transparent Conductive Oxide

Dye-sensitized solar cells (DSCs) are promising for low-cost solar electricity production. Anodes of current DSCs use mesoporous films of TiO2 nanoparticles. Although such films provide a high surface area for dye adsorption, their disordered pore structure and short electron diffusion length have limited further improvement of DSCs. ZnO nanowire-based anodes have shown promise to overcome these constraints, but their performance is limited by the intrinsic material properties of ZnO. Here, we present a DSC based on vertically aligned TiO2 nanotube arrays synthesized directly on transparent conductive oxides. It is found that the TiO2 nanotube-based DSCs significantly outperform ZnO nanowire-based ones, and the electron lifetime in TiO2 nanotubes is more than 10 times longer than those in ZnO nanowires and TiO2 nanoparticles, which leads to significantly improved electron-collecting efficiency. This result opens up numerous opportunities to further improve DSCs, for example, by employing solid-state electrolytes and redox mediators with faster kinetics.