Photoinduced intermolecular electron transfer between oligo(p-phenylene vinylene)s and N-methylfulleropyrrolidine in a polar solvent

Photoinduced intermolecular electron transfer in mixtures of oligo(p-phenylene vinylene)s (OPVns, with n=2–7, the number of phenyl rings) and N-methylfulleropyrrolidine (MP-C60) is studied in o-dichlorobenzene. Photoinduced absorption (PIA) spectroscopy is used to show that photoexcitation of MP-C60 generates the corresponding triplet state, which is quenched in a one-electron reduction reaction by OPVn for n>2. The electronic transitions of the photogenerated OPVn+ radical cations evolve with conjugation length in a near linear relation with 1/n. Charge transfer in these donor–acceptor systems for n>2 is in full agreement with the calculated change in free energy for charge separation.