Preparation of functionalized and non-functionalized fullerene thin films on ITO glasses and the application to a counter electrode in a dye-sensitized solar cell

Several thin films of [60]fullerene and the derivatives (3–5) have been prepared on ITO glasses by a common coating method using organic solutions and/or by an electrolytic micelle disruption method using surfactants with ferrocenyl moiety 2. In particular, the surface of the film formed by the electrolysis method was confirmed by SEM and AFM measurements, and then these images clearly exhibited that the entire surface of the ITO glass was uniformly covered with [60]fullerene. The UV–vis spectroscopy obviously showed that the thickness increased with the electrolysis time. For example, the thickness of the film formed by the electrolysis for 2 h was ca. 2,000 Å. Furthermore, we investigated the potential utilization as a counter electrode material instead of Pt in a dye-sensitized solar cell (DSC). Consequently, these films, except for that of derivative 5 prepared by the coating process, were found to act as a counter electrode materials in a DSC. These photovoltaic efficiencies of the films prepared by the electric micelle disruption method were higher than those of the films prepared by the common coating method. In addition, the highest efficiency was obtained in the cases with the fullerene thin film formed by the electrolysis for 2 h.