Dye-sensitized solar cells are a relatively new type of energy conversion system, which interlink the field of chemistry and physics. Functionalized molecules are adsorbed onto a TiO2 nanostructured surface. When illuminated, these functionalized molecules provide charges to the conduction band of the TiO2 particles. Many aspects of the chemical, electrical, and geometrical properties of the adsorbed molecules are still unknown. We use high-resolution atomic force microscopy to characterize single molecules and molecular assemblies on such surfaces.