Synthesis and optoelectronic behavior of conjugated polymer poly(3-hexylthiophene) grafted on multiwalled carbon nanotubes

Abstract

A nanocomposite of multiwalled carbon nanotubes (CNTs) and poly(3-hexylthiophene) (P3HT) was prepared by grafting P3HT uniformly on the surface of CNTs (P3HT/P3HT-g-CNT) via a "grafting from" method with the coating thicknesses controlled. It was found that as the coating thickness decreased, the crystallinity of the P3HT decreased, along with significant red-shifting of Raman that signified alterations of chain conformation. Furthermore, although the photoluminescence (PL) peak remained unchanged when grafted on CNTs, modifications of P3HT energy gap was observed, indicating variations of vibronic levels arising from the grafting. Moreover, broadening of the PL emission took place that suggested decreasing of lifetimes of the photo-generated species when grafted on CNTs. Bilayer photovoltaic devices with the (6,6)-phenyl C61-butyric acid methyl ester as the electron acceptor have shown that the nanocomposite P3HT/P3HT-g-CNT performed much more efficiently as the electron donor, in both photocurrent density and power conversion efficiency, compared with the neat P3HT. © 2011 Wiley Periodicals, Inc.