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.

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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