Optimal power and efficiency of single quantum dot heat engines: theory and experiment

Abstract

Quantum dots (QDs) can serve as near perfect energy filters and are therefore of significant interest for the study of thermoelectric energy conversion close to thermodynamic efficiency limits. Indeed, recent experiments in [Nat. Nano. 13, 920 (2018)] realized a QD heat engine with performance near these limits and in excellent agreement with theoretical predictions. However, these experiments also highlighted a need for more theory to help guide and understand the practical optimization of QD heat engines, in particular regarding the role of tunnel couplings on the performance at maximum power and efficiency for QDs that couple seemingly weakly to electronic reservoirs. Furthermore, these experiments also highlighted the critical role of the external load when optimizing the performance of a QD heat engine in practice. To provide further insight into the operation of these engines we use the Anderson impurity model together with a Master equation approach to perform power and efficiency calculations up to co-tunneling order. This is combined with additional thermoelectric experiments on a QD embedded in a nanowire where the power is measured using two methods. We use the measurements to present an experimental procedure for efficiently finding the external load $R_P$ which should be connected to the engine to optimize power output. Our theoretical estimates of $R_P$ show a good agreement with the experimental results, and we show that second order tunneling processes and non-linear effects have little impact close to maximum power, allowing us to derive a simple analytic expression for $R_P$. In contrast, we find that the electron contribution to the thermoelectric efficiency is significantly reduced by second order tunneling processes, even for rather weak tunnel couplings.

References in corpus (12)

• Thermoelectric energy harvesting with quantum dots
• Quantum limit of heat flow across a single electronic channel
• Giant thermopower and figure of merit in single-molecule devices
• Thermopower of a Kondo-correlated quantum dot
• Optimal thermoelectric figure of merit of a molecular junction
• Kinetic Equations for Transport Through Single-Molecule Transistors
• Giant Thermoelectric Effect from Transmission Supernodes
• Thermoelectric conversion at 30K in InAs/InP nanowire quantum dots
• Fermionic superoperators for zero-temperature non-linear transport: real-time perturbation theory and renormalization group for Anderson quantum dots
• Experiments on thermoelectric properties of quantum dots
• Non-Linear Thermovoltage in a Single-Electron Transistor
• Spin switching via quantum dot spin valves

Cited by in corpus (12)

• Comparative study of heat-driven and power-driven refrigerators with Coulomb-coupled quantum dots
• Multitask quantum thermal machines and cooperative effects
• Numerically "exact" simulations of a quantum Carnot cycle: Analysis using thermodynamic work diagrams
• Dynamics of a strongly coupled quantum heat engine -- computing bath observables from the hierarchy of pure states
• The laws of thermodynamics for quantum dissipative systems: A quasi-equilibrium Helmholtz energy approach
• Maximum Power of Coupled-Qubit Otto Engines
• The optimum configuration design of a nanostructured thermoelectric device with resonance tunneling
• Thermoelectric study of the time-dependent Resonant Level Model
• A Strongly Correlated Quantum-Dot Heat Engine with Optimal Performance: An Non-equilibrium Green's function Approach
• Current noise in quantum dot thermoelectric engines
• Heat operator approach to quantum stochastic thermodynamics in the strong-coupling regime
• The reverse flow and amplification of heat in a quantum-dot system