Length dependence of conductance and thermopower of hybrid alkyl-thiophene single molecule junctions

ORAL

Abstract

Single-molecule junctions are novel, controllable testbeds for understanding mixed electronic and thermal transport at interfaces. Here, we study a set of newly-synthesized molecules containing alkyl and thiophene units of increasing length in order to control junction level alignment and electronic coupling with~a combination of theory and experiment. Using a first-principles scattering-state approach, based on self-energy corrected density functional theory, we calculate the conductance and thermopower of thiol-terminated alkyl-thiophene-Au junctions, elucidating the relationship between length and thermopower. We compare our work to statistical measurements with a scanning tunneling microscope-based break junction technique, and discuss the impact of junction geometry on our results.

*Work supported by ONR/AFOSR BAA 10-026 and computational resources provided by NERSC.

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Authors

  • Michele Kotiuga

    • Molecular Foundry, LBNL, Department of Physics, UC Berkeley

  • William B. Chang

    • Department of Chemical and Biomolecular Engineering, UC Berkeley

  • Cheng-Kang Mai

    • University of California, Santa Barbara
    • Center for Polymers and Organic Solids, Departments of Chemistry \& Biochemistry and Materials, UCSB

  • Fabian Pauly

    • Department of Physics, Uni. Konstanz

  • Guillermo Bazan

    • University of California, Santa Barbara
    • Center for Polymers and Organic Solids, Departments of Chemistry \& Biochemistry and Materials, UCSB

  • Rachel Segalman

    • Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California
    • University of California, Berkeley
    • Dept of Chemical Engineering, UC Berkeley
    • Univ of California - Berkeley
    • Department of Chemical and Biomolecular Engineering, UC Berkeley
    • University of California-Berkeley, Lawrence Berkeley Lab

  • Jeffery B. Neaton

    • Department of Physics, UC-Berkeley; Molecular Foundry, LBNL
    • Molecular Foundry, LBNL, Department of Physics, UC Berkeley
    • Molecular Foundry, LBNL and Dept. Physics, UC Berkeley
    • Molecular Foundry, Lawrence Berkeley National Laboratory and Department of Physics, University of California, Berkeley
    • UC Berkeley, Dept of Physics; Materials Science Division, LBNL
    • Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, UC-Berkeley
    • The Molecular Foundry, LBNL; Dept. of Physics, University of California, Berkeley
    • Lawrence Berkeley National Laboratory
    • UC Berkeley Department of Physics
    • Lawrence Berkeley Natl Lab and Department of Physics, UC-Berkeley
    • Physics Department, UC Berkeley; Molecular Foundry, Lawrence Berkeley National Lab