Charge transport physics of a unique class of rigid-rod conjugated polymers with fused ring conjugated units linked by double carbon-carbon bonds

Abstract

We investigate the charge transport physics of a novel class of electron deficient conjugated polymers that do not contain any single bonds linking monomer units along the backbone, but only double bond linkages. Such polymers would be expected to behave as rigid rods but little is known about their actual chain conformations and electronic structure. Here we present a detailed study of the structural and charge transport properties of a family of four such polymers. Small angle neutron scattering provides evidence for a highly rigid chain conformation. By adopting a copolymer design we achieve high electron mobilities up to 0.5 cm2V-1s-1. Field-induced ESR measurements of charge dynamics provide evidence for relatively slow hopping over, however, long distances. Our work provides important insights into the factors that limit charge transport in this unique class of polymers and allow us to identify molecular design strategies for achieving even higher levels of performance.