Thermoelectric efficiency of quantum dot molecules at a high temperature bias: the role of thermal-induced voltage

TL;DR

This paper theoretically investigates the thermoelectric efficiency of quantum dot molecules at high temperatures, focusing on the effects of thermal-induced voltage, Coulomb interactions, and external load resistance on electron and heat currents.

Contribution

It provides new insights into the efficiency behavior of serially coupled triple quantum dots under temperature bias, including the impact of Coulomb blockade and thermal-induced bias.

Findings

Maximum efficiency occurs in the orbital depletion regime due to Coulomb blockade.

Electron current exhibits bipolar oscillations with QD energy levels, heat current does not.

Efficiency is affected by external load resistance and phonon heat flow.

Abstract

The nonlinear electron and heat currents of quantum dot molecules (QDMs) under a temperature bias are theoretically investigated, including all correlation functions arising from electron Coulomb interactions in QDMs. Unlike the case of double QDs, the maximum efficiency of serially coupled triple QDs (SCTQD) occurs in the orbital depletion regime owing to the interdot Coulomb blockade. The electron current in SCTQD shows a bipolar oscillatory behavior with respect to the variation of QD energy levels, whereas the heat current does not show such a behavior. This is mainly attributed to thermal-induced bias. In addition, we illustrate how the efficiency of SCTQD is influenced by the external load resistance, and phonon heat flow. Finally, a direction-dependent electron current driven by a temperature bias has been demonstrated for a SCTQD with staircase-like energy levels.