Performance analysis of an interacting quantum dot thermoelectric system

TL;DR

This paper investigates how Coulomb interactions in an interacting quantum dot affect thermoelectric efficiency, revealing that peak efficiency can occur at finite power and deviates from traditional figures of merit.

Contribution

It demonstrates that Coulomb interactions alter fundamental thermoelectric performance limits, allowing finite power at peak efficiency and challenging conventional $zT$ based predictions.

Findings

Reversible operation yields zero efficiency.

Finite power operation can reach near-Carnot efficiencies.

Maximum efficiency trends differ from traditional $zT$ predictions.

Abstract

We analyze the nanocaloritronic performance of an interacting quantum dot that is subject to an applied bias and an applied temperature gradient. It is now well known that, in the absence of phonon contribution, a weakly coupled non-interacting quantum dot can operate at thermoelectric efficiencies approaching the Carnot limit. However, it has also been recently pointed out that such peak efficiencies can only be achieved when operated in the reversible limit, with a vanishing current and hence a vanishing power output. In this paper, we point out three fundamental results affecting the thermoelectric performance due to the inclusion of Coulomb interactions: a) The reversible operating point carries zero efficiency, b) operation at finite power output is possible even at peak efficiencies approaching the Carnot value, and c) the evaluated trends of the the maximum efficiency deviate considerably from the conventional {\it{figure of merit}} $zT$ based result. Finally, we also analyze our system for thermoelectric operation at maximum power output.