Dye-sensitized solar cells using graphene-based counter electrode

Graphene film was fabricated using graphene oxide (GO) prepared from a modified Hummers' method. The reduction of GO (rGO) was accomplished by coating the GO paste on a piece of glass and immersing into a Ti⁺³ solution. The freeze drying (FD) process employed for drying GO before its forming of paste and coating into a film exhibits a profound effect on the quality of final graphene counter electrode. The graphene electrode obtained using freeze drying process exhibits a porous structure and is an excellent replacement for the Pt counter electrode of dye-sensitized solar cells (DSSCs). The conversion efficiency for the FD-rGO-based DSSC reaches 6.21%, which is much higher than that of the normal Pt-based DSSC 5.62% using standard P25 materials. The much more reaction sites on the porous FD-rGO-film electrode than the smooth Pt electrode are considered to be the major reason for this high performance.