Photoconducting Properties of Fullerene Derivatized with a Biphenyl Moiety

The properties of low molecular weight molecules, in which the electron-acceptor fullerene unit was linked by malonate group and flexible long alkyl chains to two biphenyl-phenyl units, were studied. Cyclic voltammetry measurements showed five consecutive one-electron, reversible electro-reductions for the fullerene unit and a single two-electron, reversible electro-oxidation for biphenyl moiety. The two electron process indicated that two biphenyl moieties interacted; presumably folded conformation was formed with two electron donating moieties at close proximity. Along-living charge-separated state induced upon light absorption was confirmed by the ESR spectroscopy studies. These properties were responsible for observed photoconductivity of the studied compound.