Role of buckminsterfullerene, C 60 , in organic polymeric photoelectric devices

Abstract

In this review we discus the photophysical properties of the supramolecular composites of two (pi) -electron semiconductors; e.g. 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 band. The Buckminsterfullerene, C 60 is a powerful acceptor moeity upon photoexcitation. Thus, the supramolecular composite of these two conjugated materials exhibit an ultrafast, reversible, metastable photoinduced electron transfer and charge separation. This process, similar to the primary steps of photosynthesis, has been utilized in conjugated polymer/C 60 based heterojunction as well as Schottky type devices for effective conversion of the solar photon energy into electricity. Other related applications of the above mentioned photophysics include photolithographic and xerographic processes. Furthermore, quantum well like heterostructures based on organic donor-acceptor layers are proposed to exhibit interesting photoinduced phenomena. Non-linear optical (NLO) properties of these composites are reported in comparative studies with the components alone. The results show a strong enhancement of the NLO coefficients in the composite materials compared to the conjugated polymer as well as C 60 alone.