Regimes and quantum bounds of nanoscale thermoelectrics with peaked transmission function

TL;DR

This paper analyzes the thermoelectric behavior of nanoscale systems with peaked transmission functions, identifying quantum bounds on power and heat currents, and classifying operational regimes without numerical simulations.

Contribution

It introduces a simple model to understand quantum bounds in thermoelectric devices with peaked transmission functions, aligning with more complex previous studies.

Findings

Quantum bounds exist for power and heat currents in nanoscale thermoelectrics.

Operational regimes include energy pump, heat pump, and dissipative modes.

The model's results agree qualitatively with more detailed previous analyses.

Abstract

Based on the Landauer-B\"{u}ttiker theory, we explore the thermal regimes of two-terminal nanoscale systems with an energy-peaked transmission function. The device is in contact with two reservoirs held at different temperatures and chemical potentials. We identify the operation regions where the system acts as energy pump (thermal machine) or heat pump (refrigerator machine), or where it is working in dissipative modes. The corresponding thermoelectric parameters are obtained without numerical calculations. The recent literature, by focusing on systems with box-like or step-like shapes of the transmission functions, demonstrated that bounds of quantum origin exist for output power and heat currents of thermal machines and refrigerators. The simple model we adopt in this paper allows us to grasp easily and without numerical calculations the presence of quantum bounds for the above thermoelectric quantities, as function of the position of the transmission peak with respect to the chemical potentials of the left and right reservoirs. In spite of the simple model and treatment, our results are in qualitative agreement with analytic findings in previous researches obtained with more realistic description of the electronic transmission function.