Synthesis and Photophysical Properties of Novel Fullerene Derivatives as Model Compounds for Bulk-Heterojunction PV Cells

Covalent and well-defined oligomer-fullerene donor-acceptor molecular structures can serve as important model systems for plastic PV cells, based on interpenetrating networks of conjugated polymers and fullerene derivatives. Two series of [60]fullerene-oligomer dyads and triads were prepared and investigated with respect to their photophysical properties such as photoinduced electron transfer using photoinduced absorption spectroscopy. We report here on a series of fullerene-oligothiophene-fullerene triads with ter-, sexi- and novithienyl donor moieties and on a homologous series of oligo [phenylenevinylene]-fullerene dyads. Measurements on these novel structures both in solution and in the solid state reveal that the environment plays a crucial role in the formation and lifetime of the various photoinduced charged states in these molecules