Effect of sodium on photovoltaic properties of dye-sensitized solar cells assembled with anatase TiO2 nanosheets with exposed {001} facets

[Display omitted] ► Na+ containing TiO2 nanosheets with exposed {001} facets were synthesized. ► Increased charge recombination was revealed in Na+ containing TiO2 nanosheets. ► XPS confirmed the presence of Na+ is responsible for the reduced efficiency in DSSCs. Anatase TiO2 nanosheets with exposed reactive {001} facets were prepared in the presence of HF. The photovoltaic properties of NaOH-washed anatase TiO2 nanosheets with exposed {001} facets were investigated by assembling the TiO2 as photoanodes in dye-sensitized solar cells (DSSCs). A decreased overall efficiency and increased recombination rate was observed in comparison with the H2O-washed counterpart by both dark current scan and open-circuit voltage decay scan, and XPS confirmed that the deleterious effect of sodium ions is responsible for this reduced efficiency in DSSCs.