Thermoelectrics with Coulomb coupled quantum dots

TL;DR

This paper reviews recent experimental and theoretical advances in thermoelectric devices using Coulomb coupled quantum dots, highlighting thermal gating effects and nano-scale heat engine applications with decoupled heat and charge flows.

Contribution

It provides a comprehensive review of experimental observations and model calculations for Coulomb coupled quantum dot thermoelectrics, including thermal gating and heat engine functionalities.

Findings

Thermal gating enables remote control of charge flow via temperature.

Two regimes identified: small heat flow with occupation fluctuation effects, and significant heat flow functioning as a nano-scale heat engine.

Decoupling of heat and charge flow in quantum dot thermoelectric devices.

Abstract

In this article we review the thermoelectric properties of three terminal devices with Coulomb coupled quantum dots (QDs) as observed in recent experiments [1,2]. The system we consider consists of two Coulomb-blockade QDs one of which can exchange electrons with only a single reservoir (heat reservoir) while the other dot is tunnel coupled to two reservoirs at a lower temperature (conductor). The heat reservoir and the conductor interact only via the Coulomb-coupling of the quantum dots. It has been found that two regimes have to be considered. In the first one heat flow between the two systems is small. In this regime thermally driven occupation fluctuations of the hot QD modify the transport properties of the conductor system. This leads to an effect called thermal gating. Experiment have shown how this can be used to control charge flow in the conductor by means of temperature in a remote reservoir. We further substantiate the observations with model calculations and implications for the realization of an all-thermal transistor are discussed. In the second regime, heat flow between the two systems is relevant. Here the system works as a nano scale heat engine, as proposed recently [3]. We review the conceptual idea, its experimental realization and the novel features arising in this new kind of thermoelectric device such as decoupling of heat and charge flow.