The investigation of donor-acceptor compatibility in bulk-heterojunction polymer systems

Abstract

The fullerene derivative, indene-C60 bisadduct (ICBA), has been introduced into poly(3-hexylthiophene) (P3HT) to improve the efficiency of P3HT-based devices. However, we found that ICBA is not suitable for most low bandgap polymers. In this study, we have correlated the cell performance with surface energy between the donor and acceptor materials in a bulk-heterojunction cell. These results show that higher photocurrent can be attributed to the morphology improvement induced by larger surface energy difference (Δγ) between the low bandgap polymer and fullerene. These results also suggest that synthetic strategies which adjust the Δγ between donor and acceptor should be considered.