Role of Buckminsterfullerene, C60, in organic photoelectric devices

In this review we discuss the photophysical properties of the supramolecular composites of two π-electron semiconductors; conjugated polymers as electron donors and Buckminsterfullerene as electron acceptor. Conjugated, polymeric semiconductors have been found to be effective donors upon photoexcitation of the valence band electrons across the bandgap into the conduction bands. The Buckminsterfullerene, C60, acts as a strong acceptor upon photoexcitation. Thus, the supramolecular composite of these two conjugated materials exhibit ultrafast, reversible, metastable photoinduced electron transfer and charge separation. This process, similar to the primary steps of photosynthesis, has been utilized in conjugated polymer/C60 based heterojunction as well as in metal-semiconductor-metal tunnel devices for effective conversion of the solar photon energy into electricity. Other related applications of the photophysics, including photolithographic and xerographic processes, are reviewed. Furthermore, recent developments on light emitting diodes and solar cells with anomalous behavior based on Buckminsterfullerene are critically reviewed. Quantum well-like heterostructures based on organic donor-acceptor layers are proposed to exhibit interesting photoinduced phenomena.