Zinc-doped SnO₂ nanocrystals as photoanode materials for highly efficient dye-sensitized solar cells

Zn-doped SnO₂ nanocrystals were successfully synthesized by a simple hydrothermal method. It is found that Zn doping into SnO₂ can induce a negative shift in the flat-band potential (V_FB) and increase the isoelectric point. As a result, dye-sensitized solar cells (DSCs) based on Zn-doped SnO₂ nanocrystal photoanodes exhibit longer electron lifetimes and higher dye loading compared to undoped SnO₂ based DSCs. The overall power conversion efficiency (η) of the optimized Zn-doped SnO₂ based DSC reaches 4.18% and increases to 7.70% after the TiCl₄ treatment. More importantly, a remarkable η of 8.23% is achieved for DSCs based on a high-quality double-layer SnO₂ photoanode with the TiCl₄ treatment, to the best of our knowledge, which is so far the best reported efficiency for DSCs based on SnO₂ photoanodes.