Nonlinear thermoelectric efficiency of superlattice-structured nanowires

TL;DR

This paper theoretically explores how superlattice-structured nanowires can achieve high nonlinear thermoelectric efficiency by optimizing barrier widths, with implications for practical nanowire thermoelectric generators.

Contribution

It introduces a method to design nanowire superlattices with near-ideal transmission profiles to enhance thermoelectric efficiency, considering realistic imperfections.

Findings

High thermoelectric efficiency is achievable with optimized superlattice structures.

Efficiency remains high at significant power outputs.

Results are applicable with current nanowire fabrication technologies.

Abstract

We theoretically investigate nonlinear ballistic thermoelectric transport in a superlattice-structured nanowire. By a special choice of nonuniform widths of the superlattice barriers - analogous to anti-reflection coating in optical systems - it is possible to achieve a transmission which comes close to a square profile as a function of energy. We calculate the low-temperature output power and power-conversion efficiency of a thermoelectric generator based on such a structure and show that the efficiency remains high also when operating at a significant power. To provide guidelines for experiments, we study how the results depend on the nanowire radius, the number of barriers, and on random imperfections in barrier width and separation. Our results indicate that high efficiencies can indeed be achieved with todays capabilities in epitaxial nanowire growth.