Graphene-titania films by supersonic kinetic spraying for enhanced performance of dye-sensitized solar cells

Graphene-titania films were fabricated by supersonic kinetic spray, known as aerosol deposition. Graphene concentration was varied to fabricate 0.1, 0.3, 0.5, 0.7, and 1.0 wt% G-TiO₂ films for dye-sensitized solar cell (DSSC) application and to investigate the effect of graphene concentration on their energy conversion efficiency. The G-TiO₂ films were characterized and analyzed based on results from SEM, XRD, XPS, TEM, and the current-voltage curve. The optimal concentration was 0.3 wt%, which decreased the recombination rate, favoring the formation of photogenerated electron-hole pairs. As a result, the conversion efficiency was 5.02% while that of the pure TiO₂ was 3.14%. A clear trend per various concentrations was observed. At higher concentrations than 0.3 wt%, the conversion efficiency decreased owing to higher absorption of light by graphene present on the surface, thus reducing the generation of electron-hole pairs.