Influence of Side-chain Chemistry on Structure and Ionic Conduction Characteristics of Polythiophene Derivatives: A Computational and Experimental Study

ORAL

Abstract

While extensive efforts have been devoted to understand electronic transport in conjugated polymers, little is known about their ionic conduction characteristics in relation to polymer chemistry and morphology. This work presents a combined computational and experimental study on morphology and ion transport in thin film blends of polythiophene derivatives and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Using molecular dynamics (MD) simulation, we show that in the amorphous phase, a polythiophene derivative P3EGT bearing oligoethylene glycol side-chains with an oxygen directly attached to the thiophene rings possesses lower Li+ ion conductivity compared to its analog P3MEGT that has a methyl spacer between the oxygen and the thiophene rings. Structural characterization of P3EGT- and P3MEGT-LiTFSI thin films indicates that LiTFSI preferably resides in the amorphous domain especially at high LiTFSI concentrations. Ionic transport measured by impedance spectroscopy is found to occur in amorphous domain, and ionic conductivity in P3MEGT is always higher than in P3EGT, consistent with prediction from simulation. Our work provides a platform to predict and study the influence of polymer chemistry on ionic conductivity of conjugated polymers.

*NSF DMREF Award Number 1629369

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Presenters

  • Ban Dong

    • Institute for Molecular Engineering, University of Chicago
    • University of Chicago

Authors

  • Ban Dong

    • Institute for Molecular Engineering, University of Chicago
    • University of Chicago

  • Christian Nowak

    • School of Chemical and Biomolecular Engineering, Cornell University

  • Jonathan Onorato

    • Department of Materials Science and Engineering, University of Washington
    • Materials Science and Engineering Department, University of Washington

  • Fernando A Escobedo

    • School of Chemical and Biomolecular Engineering, Cornell University
    • Cornell University
    • Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University
    • Chemical and Biomolecular Engineering, Cornell University

  • Christine Luscombe

    • Department of Materials Science and Engineering, University of Washington
    • Materials Science and Engineering Department, University of Washington

  • Paul F Nealey

    • Institute for Molecular Engineering, University of Chicago
    • University of Chicago
    • Institute for Molecular Engineering, Argonne National Laboratory

  • Shrayesh Patel

    • Institute for Molecular Engineering, University of Chicago
    • University of Chicago