Relation of Ru(II) dye desorption from TiO2 film during illumination with photocurrent decrease of dye-sensitized solar cells

The initial decrease in the short-circuit photocurrent density (Jsc) of a Ru(II)–bipyridine dye-sensitized solar cell (DSSC) during illumination is correlated with the decrease in the amount of remaining dye adsorbed on the TiO2 film monitored by UV–vis absorption spectroscopy. The analyses reveal that the illumination causes the N719 dye molecules to desorb from the TiO2 film into the electrolytic solution. The amount of dye remaining adsorbed on the TiO2 film is influenced by the viscosity and donor number of the electrolytic solution. More dye molecules remain adsorbed on the TiO2 film in the solution of 3-methoxypropionitrile than in the less viscous solution of acetonitrile. The addition of water and Triton X-100 to the 3-methoxypropionitrile solution results in the enhancement of the dye desorption, partly due to the increase in the donor number.