Wiedemann-Franz Law for Molecular Hopping Transport

Galen T. Craven, Abraham Nitzan

Research output: Contribution to journalArticlepeer-review

Abstract

The Wiedemann-Franz (WF) law is a fundamental result in solid-state physics that relates the thermal and electrical conductivity of a metal. It is derived from the predominant transport mechanism in metals: The motion of quasi-free charge-carrying particles. Here, an equivalent WF relationship is developed for molecular systems in which charge carriers are moving not as free particles but instead hop between redox sites. We derive a concise analytical relationship between the electrical and thermal conductivity generated by electron hopping in molecular systems and find that the linear temperature dependence of their ratio as expressed in the standard WF law is replaced by a linear dependence on the nuclear reorganization energy associated with the electron hopping process. The robustness of the molecular WF relation is confirmed by examining the conductance properties of a paradigmatic molecular junction. This result opens a new way to analyze conductivity in molecular systems, with possible applications advancing the design of molecular technologies that derive their function from electrical and/or thermal conductance.

Original languageEnglish
Pages (from-to)989-993
Number of pages5
JournalNano Letters
Volume20
Issue number2
DOIs
StatePublished - 12 Feb 2020

Keywords

  • Wiedemann-Franz law
  • electrical conductivity
  • molecular electronics
  • molecular junction
  • thermal conductivity

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