Enhancement of power conversion efficiency of dye sensitized solar cells by modifying mesoporous TiO2 photoanode with Al-doped TiO2 layer

The optimization of charge transfer at the TiO 2 /dye/electrolyte interface is crucial to the design of dye-sensitized solar cells. In this paper, the Al doped TiO 2 layers were coated on the mesoporous TiO 2 films by a chemical bath deposition process, followed by sintering at 500   °C. Its performance as the TiO 2 /dye/electrolyte interface layer was investigated. The analysis results reveals that the Al doped TiO 2 coating can reduce the oxygen vacancy-Ti 3+ concentrations in the photoanodes significantly, which is beneficial to suppress the back electron transfer process from TiO 2 to electrolyte. Furthermore, the electron mobility of the modified photoanodes was increased. Consequently, the dye sensitized solar cells (DSSC) based on the photoanodes modified by Al-doped TiO 2 coating show an improvement on both enhancing the electron transport and suppressing the charge recombination process. The dye sensitized solar cell based on the photoanode modified by 1.0   mol% Al-doped TiO 2 layer, shows a power conversion efficiency as high as 7.66%, increasing 9.12% compared with the unmodified reference cell. Finally, our works show a facile and scalable technique to further optimize interfacial charge transfer process in dye sensitized solar cells.