ABSTRACTAsymmetrically substituted oligo(phenylene ethynylene) (OPE) derivatives have been prepared by a new iterative method and attached to C₆₀ molecules by a 1,3-dipolar cycloaddition of the azomethine ylides generated in situ from the corresponding aldehydes and sarcosine. The molecules obtained are suitable for the fabrication of photovoltaic devices based on interpenetrating networks of donors and acceptors, with a characteristic length scale of the network topology smaller than the exciton diffusion length. We have constructed a number of photovoltaic cells incorporating the C₆₀-OPEs as the active material between two energetically asymmetric electrode contacts. The device performance has been examined and the functional characteristics have been determined too. These seem to depend systematically on the nature of the attached end-group and on the length of the donating moiety.