Quantum interference and structure-dependent orbital-filling effects on the thermoelectric properties of quantum dot molecules

TL;DR

This paper investigates how quantum interference and orbital filling influence thermoelectric properties in quantum dot molecules, revealing conditions for enhanced thermoelectric performance and guiding nanoscale device design.

Contribution

It provides a full theoretical analysis of quantum interference effects on thermoelectric properties in quantum dot molecules using the Hubbard- Anderson model.

Findings

Destructive quantum interference can suppress electrical conductance.

Seebeck coefficient varies dramatically with charge localization and temperature.

Maximum power factor depends on filling conditions and quantum dot configuration.

Abstract

The quantum interference and orbital filling effects on the thermoelectric (TE) properties of quantum dot molecules with high figure of merit are illustrated via the full solution to the Hubbard- Anderson model in the Coulomb blockade regime. It is found that under certain condition in the triangular QD molecule (TQDM), destructive quantum interference (QI) can occur, which leads to vanishing small electrical conductance, while the Seebeck coefficient is modified dramatically. When TQDM is in the charge localization state due to QI, the Seebeck coefficient is seriously suppressed at low temperature, but highly enhanced at high temperature. Meanwhile, the behavior of Lorenz number reveals that it is easier to block charge transport via destructive QI than the electron heat transport at high temperatures. The maximum power factor (PF) in TQDM occurs at full-filling condition. Nevertheless, low-filling condition is preferred for getting maximum PF in serially coupled triple QDs in general. In double QDs, the maximum PF can be achieved either with orbital-depletion or orbital-filling as a result of electron-hole symmetry. Our theoretical work provides a useful guideline for advancing the nanoscale TE technology.