Effective medium theory of binary thermoelectrics

TL;DR

This paper investigates how disorder affects thermoelectric properties in binary materials, revealing conditions where disorder enhances power factor but not overall efficiency, and highlighting the complex relationship between electrical and thermal conductivities.

Contribution

It introduces an effective medium theory combined with numerical simulations to analyze disordered thermoelectric media, identifying parameter ranges where disorder improves power factor.

Findings

Disorder can enhance the thermoelectric power factor.

Electrical conductivity and thermal conductivity are not always proportional in disordered media.

Disorder does not necessarily increase the figure of merit ZT.

Abstract

The transport coefficients of disordered media are analyzed using direct numerical simulation and effective medium theory. The results indicate a range of materials parameters for which disorder leads to an enhanced power factor. This increase in power factor is generally not accompanied by an increase in the figure of merit $ZT$, however. It is also found that the effective electrical conductivity and electronic contribution to the thermal conductivity are not generally proportional to each other in the presence of disorder.