High-Temperature Annealing of TiO2 Nanotube Membranes for Efficient Dye-Sensitized Solar Cells

We fabricate photo-anodes by transferring anodic TiO2 nanotube membranes in tube-top-down configuration on FTO glass, and use them for constructing frontside illuminated dye-sensitized solar cells. Prior to solar cell construction, the tube-based photo-anodes are crystallized at different temperatures (400-800{\deg}C), and the effects of tube electron transport properties on the photovoltaic performance of the solar cells are investigated. We show that improved solar cell efficiencies (up to ca. 8.0%) can be reached by high-temperature treatment of the tube membranes. Consistently with electron transport time measurements, remarkably enhanced electron mobility is enabled when tube membranes are crystallized at 600{\deg}C.