Seebeck coefficient of thermoelectric moleculat junction: First-principles calculations

TL;DR

This paper presents a first-principles method to analyze the Seebeck coefficient in molecular junctions, revealing how amino-substitution and external controls like gate voltages modulate thermoelectric properties.

Contribution

It introduces a novel first-principles approach to study thermoelectric effects in molecular junctions, highlighting the impact of molecular modifications and external biases.

Findings

Amino-substitution introduces states that significantly affect the Seebeck coefficient.

Gate voltages effectively modulate the thermoelectric response.

Seebeck coefficient varies with electrode temperature differences and bias voltages.

Abstract

A first-principles approach is presented for the thermoelectricity in molecular junctions formed by a single molecule contact. The study investigates the Seebeck coefficient considering the source-drain electrodes with distinct temperatures and chemical potentials in a three-terminal geometry junction. We compare the Seebeck coefficient in the amino-substituted and unsubstituted butanethiol junction and observe interesting thermoelectric properties in the amino-substituted junction. Due to the novel states around the Fermi levels introduced by the amino-substitution, the Seebeck coefficient could be easily modulated by using gate voltages and biases. When the temperature in one of the electrodes is fixed, the Seebeck coefficient varies significantly with the temperature in the other electrode, and such dependence could be modulated by varying the gate voltages. As the biases increase, richer features in the Seebeck coefficient are observed, which are closely related to the transmission functions in the vicinity of the left and right Fermi levels.