Nitrogen-doped TiO2 nanoparticles better TiO2 nanotube array photo-anodes for dye sensitized solar cells

Abstract

Power conversion efficiency of dye sensitized solar cell (DSSC) is closely related to photo-anode's structure. It has been believed that titanium dioxide (TiO2) nanotube array thin film is one of the best photo-anode candidates for DSSC. However, the insufficient internal surface area and wide band gap of pure anatase limit their power conversion efficiency. Here we report a novel TiO2 nanotube array film synthesized by anodization followed by surface modification with nitrogen (N) doped TiO2 nanoparticles using a solvothermal method. The incorporation of N doped TiO2 nanoparticles along the wall of TiO2 nanotubes not only provides a large surface area for dye loading, but also increases the conductivity of the electrode, generating an overall power conversion efficiency of 2.53%, which is 68% higher than that with pure TiO2 nanotube array (with the length of 1.8μm) photoanode. When the length of TiO2 nanotube increased to 4.1μm, the overall power conversion efficiency can be improved to be 4.9%, which is higher than the previous reported results using the same length of nanotube.