Self-organized film of ultra-fine TiO2 nanotubes and its application to dye-sensitized solar cells on a flexible Ti-foil substrate

One dimensional structures of TiO2 (nanowires and nanotubes) are promising for dye-sensitized solar cells due to reduced electron recombination; however, the small surface area is the main hurdle in the application of one dimensional anatase structures to dye-sensitized solar cells because of insufficient dye adsorption. Here, we address this problem with the preparation of a TiO2 nanotube film with a high specific surface area. This film was self-assembled by ultra-fine TiO2 nanotubes with diameter <10 nm via a simple hydrothermal method, and was applied to dye-sensitized solar cells on flexible Ti metal using a transplanting technique. Due to the higher surface area and one-dimensional structure, 6.23% efficiency was obtained with this ultra-fine TiO2 nanotube film, which was superior to that of conventional TiO2 nanoparticles.