title: Excitonic energy migration in conjugated polymers: the critical role of interchain morphology.
abstract: Excitonic energy migration was studied using single molecule spectroscopy of individual conjugated polymer (CP) chains and aggregates. To probe the effect of interchain morphology on energy migration in CP, tailored interchain morphologies were achieved using solvent vapor annealing to construct polymer aggregates, which were then studied with single aggregate spectroscopy. We report that highly ordered interchain packing in regioregular poly(3-hexylthiophene) (rr-P3HT) enables long-range interchain energy migration, while disordered packing in regiorandom poly(3-hexylthiophene) (rra-P3HT), even in aggregates of just a few chains, can dramatically impede the interchain mechanism. In contrast to rr-P3HT, interchain energy migration in poly(3-(2'-methoxy-5'-octylphenyl)thiophene) (POMeOPT), a polythiophene derivative with bulky side chains, can be completely inhibited. We use simulated structures to show that the reduction in interchain coupling is not due simply to increased packing distance between backbones of different chains, but reflects inhibition of stacking due to side-chain-induced twisting of the contours of individual chains. A competition from intrachain coupling has also been demonstrated by comparing POMeOPT aggregates with different polymer chain sizes.
authors.affiliation: Center for Nano and Molecular Science and Technology, Department of Chemistry, University of Texas , Austin, Texas 78712, United States.
authors.forename: Zhongjian
authors.initials: Z
authors.lastname: Hu
authors.forename: Takuji
authors.initials: T
authors.lastname: Adachi
authors.forename: Ryan
authors.initials: R
authors.lastname: Haws
authors.forename: Bo
authors.initials: B
authors.lastname: Shuang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ono
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Bielawski
authors.forename: Christy F
authors.initials: CF
authors.lastname: Landes
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Rossky
authors.forename: David A
authors.initials: DA
authors.lastname: Vanden Bout