Efficiency enhancement of dye-sensitized solar cells by the addition of an oxidizing agent to the TiO₂ paste

The addition of various amounts of a strong oxidizing agent (3,5-dinitrosalicyclic acid, DNSA) to TiO₂ paste enhances the solar-to-electrical-energy conversion efficiency of the corresponding dye-sensitized solar cells (DSSCs). Maximum performance was obtained from a device that was fabricated by using a TiO₂ paste with 2wt % DNSA, which showed a short-circuit current density of 17.88mA cm^-2, an open-circuit voltage of 0.78V, and an overall conversion efficiency of 9.62 %, which was an improvement in comparison to reference cells without DNSA. This improvement was rationalized in terms of the amount of residual carbon (formed due to the oxidation of binders) remaining on the TiO₂ surface. Addition of a larger amount of oxidizing agent led to a smaller amount of residual carbon on the TiO₂ surface. This smaller amount of residual carbon enhanced the adsorption of a larger number of dye molecules on the TiO₂ surface. The addition of an oxidizing agent facilitated the removal of more residual organic species during the high-temperature calcination process while causing no change in the surface morphology and microstructure of the TiO₂ film. Cut and paste Addition of a strong oxidizing agent (3,5-dinitrosalicylic acid) to the TiO₂ paste facilitates the exothermic burning of organic binders during the high temperature calcination process, resulting in smaller amounts of residual carbon. This reduced carbon content facilitates the adsorption of more dye molecules on the TiO₂ surface and results in a higher efficiency of the cell.