Thermoelectric properties of molecular nanostructures

TL;DR

This paper investigates the thermoelectric properties of molecular nanostructures using resonant tunneling, revealing how the thermovoltage sign depends on molecular orbitals and aligning well with experimental data.

Contribution

It introduces a resonant tunneling approach to calculate thermopower in molecular nanosystems, highlighting the orbital-dependent sign change of thermovoltage.

Findings

Thermovoltage sign depends on the molecular orbital involved.

Switching from HOMO to LUMO causes a sign change in thermovoltage.

Model results agree with recent STM experimental data.

Abstract

We use the concept of resonant tunneling to calculate the thermopower of molecular nanosystems. It turns out that the sign of the thermovoltage under resonant tunneling conditions depends sensitively on the participating molecular orbital, and one finds a sign change when the transport channel switches from the highest occupied molecular orbital to the lowest unoccupied molecular orbital. Comparing our results to recent experimental data obtained for a BDT molecule contacted with an STM tip, we observe good agreement.