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.