Ultrafast energy and electron transfer in donor-acceptor molecules for photovoltaics

Summary form only given. The rapid advancement in fullerene chemistry allows the covalent functionalization of C/sub 60/ with electron donors. Various C/sub 60/-based donor-acceptor dyads have been synthesized and studied to gain insight in the intramolecular photophysical processes, like energy and electron transfer. Although these dyads can serve as a model compounds for the conjugated photovoltaic cells, only a few examples have been reported with these C/sub 60/-based dyads. Apart from being well-defined model systems for photophysical characterization, the covalent linkage between donor,and acceptor in these molecular arrays provides a simple method to achieve control over the phase segregation in donor-acceptor networks. We investigate an oligo(phenylene vinylene)fullerene dyad with 4 phenyl groups (C/sub 60/-OPV/sub 4/) in solvents of different polarity using femtosecond pump-probe spectroscopy. We find that photoexcitation of the oligomer leads first to an intramolecular energy transfer to the fullerene, while an electron transfer is a secondary process, only allowed in polar solvents.