Influence of micelle charge density on adsorption and exciton delocalization of conjugated polyelectrolytes

Among the large set of molecular light harvesters, conjugated polyelectrolytes (CPE) stand apart due to the chain connectivity of ionic subunits, and to the strong coupling between electronic and ionic degrees of freedom. Substantial questions remain about precisely how soft molecular scaffolds can be used to tune the backbone electronic structure. We have used mixed ionic/nonionic micelles as model soft assemblies, wherein by tuning the micelle composition, we have investigated the influence of surface charge density and sign of the surface charge on the CPE/micelle interaction. We find that both the micelle charge density and the precise arrangement of charged sidechains along the CPE conspire to determine the conformational ensemble of accessible CPE states. Further, the sidechain positioning along the backbone determine whether the adsorbed CPE chain is either contorted or highly extended, leading to relatively localized or delocalized excitons, respectively.