The electron donor/acceptor approach is an effective way to convert solar energy into electrical energy in organic photovoltaic solar cells. The organic conjugated polymers have been widely used as donor constituents. The polymers of C₆₀ and transition metals are good candidates for the electron-accepting components. In the coordination fullerene polymers, C₆₀ moieties are bounded with transition metal atoms or complexes into three-dimensional polymeric network. The most intensively investigated polymer of C₆₀ and palladium atoms, poly-Pd₃C₆₀, exhibits an ordered body centered cubic (bcc) structure of fullerene units with a slight rombohedral distortion. The fullerene cage is octohedrally coordinated by six palladium atoms. Each palladium atom is bounded to two C₆₀units.

Hybrid materials composed of n-doped fullerene/transition metal complex polymers and polypyrrole were formed under electrochemical or chemical conditions. The electrochemically synthesis, bilayers of both materials exhibit rectifying characteristics and can serve as a charge trapping system.

The core shell nanoparticles, i.e., poly-Pd₃C₆₀@polypyrrole (Figure 1), were prepared by sequential chemical polymerization of both components. These systems can be used for the modeling of the charge transfer processes in bulk-heterojunction solar devices. The outer polypyrrole layer is easily oxidized at potentials corresponding to the potentials of pure polypyrrole oxidation. The poly-Pd₃C₆₀ core reduction is shifted toward more negative potentials in comparison to the potential of reduction of pure poly-Pd₃C₆₀. The electrochemical measurements reveal that poly-Pd₃C₆₀@polypyrrole with outer polypyrrole layer doped with light harvesting molecules and thinner than about 20 nm can be potentially used in solar energy conversion electrochemical devices. The small thickness of the outer layer prevents free charge carriers recombination. The large area of p-n nanojunction in nanostructured material should increase efficiency of solar energy conversion. The electric charge formed at the p-n nanojunction can be also transferred from poly-Pd₃C₆₀inner sphere to the metallic collector.