Thermoelectric effect in molecular junctions: A tool for revealing transport mechanisms

TL;DR

This paper demonstrates that thermoelectric measurements in molecular junctions can reveal detailed electron transport mechanisms and Fermi level positioning, providing insights beyond standard current-voltage analysis.

Contribution

It introduces analytical and numerical methods to use thermopower as a tool for understanding electron transfer mechanisms in molecular junctions.

Findings

Thermoelectric potential indicates transport mechanisms like coherent transmission and hopping.

High-temperature thermopower reveals Fermi energy position relative to molecular states.

Standard I-V measurements do not provide this detailed information.

Abstract

We investigate the thermopower of a metal-molecule-metal junction taking into account thermal effects on the junction. Based on analytical expressions and numerical simulations we show that the thermoelectric potential reveals valuable information on the mechanisms controlling the electron transfer process, including coherent transmission and thermalized hopping. We also show that at high temperatures the position of the Fermi energy relative to the molecular states can be easily deduced from the thermoelectric potential. Standard current-voltage measurements are insensitive to this information.