Thermoelectric efficiency at maximum power in low-dimensional systems

TL;DR

This paper compares the efficiency at maximum power of low-dimensional thermoelectric systems, finding 1D conductors outperform quantum dots and discussing implications for thermoelectric device design.

Contribution

It provides a comparative analysis of three low-dimensional thermoelectric systems' efficiency at maximum power, highlighting the superior performance of 1D conductors.

Findings

1D conductors achieve up to 36% of Carnot efficiency.

Quantum dots show lower efficiency and power at maximum power.

Efficiency at maximum power is temperature-independent across systems.

Abstract

Low-dimensional electronic systems in thermoelectrics have the potential to achieve high thermal-to-electric energy conversion efficiency. A key measure of performance is the efficiency when the device is operated under maximum power conditions. Here we study the efficiency at maximum power of three low-dimensional, thermoelectric systems: a zero-dimensional quantum dot (QD) with a Lorentzian transmission resonance of finite width, a one-dimensional (1D) ballistic conductor, and a thermionic (TI) power generator formed by a two-dimensional energy barrier. In all three systems, the efficiency at maximum power is independent of temperature, and in each case a careful tuning of relevant energies is required to achieve maximal performance. We find that quantum dots perform relatively poorly under maximum power conditions, with relatively low efficiency and small power throughput. Ideal one-dimensional conductors offer the highest efficiency at maximum power (36% of the Carnot efficiency). Whether 1D or TI systems achieve the larger maximum power output depends on temperature and area filling factor. These results are also discussed in the context of the traditional figure of merit $ZT$.