Thermoelectric properties of a weakly coupled quantum dot: enhanced thermoelectric efficiency

TL;DR

This paper investigates the thermoelectric properties of a multi-level quantum dot in the Coulomb blockade regime, revealing a giant enhancement of efficiency due to quantum confinement and phonon freezing effects.

Contribution

It provides analytical expressions and detailed analysis of thermoelectric coefficients in quantum dots, highlighting the impact of energy level separation and phonon effects on efficiency.

Findings

Giant enhancement of the figure of merit due to violation of Wiedemann-Franz law.

Activated behavior of electronic and phonon thermal conductance.

Potential for improved thermoelectric nanostructures through confinement control.

Abstract

We study the thermoelectric coefficients of a multi-level quantum dot (QD) weakly coupled to two electron reservoirs in the Coulomb blockade regime. Detailed calculations and analytical expressions of the power factor and the figure of merit are presented. We restrict our interest to the limit where the energy separation between successive energy levels is much larger than the thermal energy (i.e., the quantum limit) and we report a giant enhancement of the figure of merit due to the violation of the Wiedemann-Franz law when phonons are frozen. We point out the similarity of the electronic and the phonon contribution to the thermal conductance for zero dimensional electrons and phonons. Both contributions show an activated behavior. Our findings suggest that the control of the electron and phonon confinement effects can lead to nanostructures with improved thermoelectric properties.