Charge transfer kinetics in fullerene-oligomer-fullerene triads containing alkylpyrrole units

A photoinduced electron-transfer reaction has been obsd. in three fullerene-donor-fullerene triads contg. an electron-rich pyrrole ring in the donor moiety. The kinetics of charge sepn. in soln. has been investigated by photoluminescence and transient absorption spectroscopy. The polarity of solvent and the distance between donor and acceptor affect the forward electron-transfer reaction, in qual. agreement with a semiempirical model for the Gibbs free energy for charge sepn. Depending on the conditions, charge sepn. occurs at a rate of 109-1010 s-1. The charge recombination rate is estd. to be faster than 2 * 1010 s-1. The relatively large contribution of the singlet-excited-state Sn -> S1 absorption of the fullerene moiety to the photoinduced absorption hampered a more accurate detn. of the recombination rate. [on SciFinder (R)