Enhanced electron diffusion length of mesoporous TiO2 film by using Nb2O5 energy barrier for dye-sensitized solar cells

Electron diffusion coefficient (D) and electron lifetime (τ) of mesoporous TiO2 films with Nb2O5 energy barrier were investigated by the stepped light-induced transient measurements of photocurrent and photovoltage, compared with that without the Nb2O5. Both the D and τ values were significantly increased with the Nb2O5 energy barrier, resulting in remarkable enhancements of electron diffusion length and optimum thickness of the TiO2 film. As a result, the Nb2O5 energy barrier could provide much more efficient dye-sensitized solar cells by the additional effect of the improved optimum thickness as well as the existing effect at the same TiO2 film thickness.