Enhancement of the thermoelectric efficiency in a T-shaped quantum dot system in the linear and nonlinear regimes

TL;DR

This study investigates how interference effects, Coulomb interactions, and Van-Hove singularities influence the thermoelectric efficiency of a T-shaped double quantum dot system, revealing conditions for significant efficiency enhancement.

Contribution

It demonstrates the impact of Van-Hove singularities and Coulomb blockade on thermoelectric performance in a T-shaped quantum dot system, using Hubbard III approximation.

Findings

Enhanced thermopower and figure of merit in linear response.

High thermoelectric efficiency and power output in nonlinear regime.

Van-Hove singularity significantly boosts thermoelectric efficiency.

Abstract

In the present work, we investigate the thermoelectric properties of a T-shaped double quantum dot system coupled to two metallic leads incorporating the intra-dot Coulomb interaction. We explore the role of the interference effects and Coulomb blockade on the thermoelectric efficiency of the system in the linear and nonlinear regimes. We studied as well the effect of a Van-Hove singularity of the leads density of states (DOS) at the neighborhood of the Fermi energy, a situation that can be obtained using a carbon nanotube, a graphene nano-ribbon or other contacts with one-dimensional properties. The system is studied above the Kondo temperature. The Coulomb blockade of the electronic charges is studied using the Hubbard III approximation, which properly describes the transport properties of this regime. In the linear response, our results show an enhancement of the thermopower and the figure of merit of the system. For a nonlinear situation, we calculate the thermoelectric efficiency and power output, concluding that the T-shaped double quantum dot is an efficient thermoelectric device. Moreover, we demonstrate the great importance of the DOS Van-Hove singularity at the neighborhood of the Fermi energy to obtain a very significant increase of the thermoelectric efficiency of the system.