Sensitizer activated solar cells based on self-organized TiO2 nanotubes

Self-ordered 1D nanostructures currently attract increasing interest due to their controlled geometry associated with unique structural and morphological characteristics. Vertically oriented TiO2 nanotubes (NTs) grown by electrochemical anodization provide a robust substrate for efficient solar-energy conversion. In this work, we report on the preparation of NTs under low applied voltage (+30 V vs. Pt) in NH4F/ethylene glycol electrolytes containing a slight amount of water. The effects of the Ti foils polishing (before anodization) and the removal of the nanograss (structural disorder created at the top surface of the NTs due to the prolonged exposure of the tubes inside the F− rich environment) on the nanotubular films properties are investigated. After optimization of the anodization conditions, homogeneous anodic films consisting of smooth and long NTs are prepared, which, when incorporated as photoelectrodes in dye-sensitized solar cells, present an overall power conversion efficiencies of about 3% under backside illumination conditions.