Theory of ZT enhancement in nanocomposite materials

TL;DR

This paper presents a theoretical analysis of how interface scattering in nanocomposite materials can enhance thermoelectric performance, identifying key interfacial properties needed for ZT improvement.

Contribution

It introduces a theoretical framework linking interface scattering properties to ZT enhancement in nanocomposites, based on effective medium theory and numerical simulations.

Findings

ZT enhancement depends on specific interfacial electrical conductance

Thermal phonon conductance must be below a critical threshold

Enhancement conditions relate to bulk material properties and Z ratios

Abstract

The effect of interface scattering on the performance of disordered, nanocomposite thermoelectric materials is studied theoretically using effective medium theory and direct numerics. The interfacial electronic and phonon scattering properties which lead to an enhancement of the thermoelectric figure of merit $ZT$ are described. Generally, $ZT$ enhancement requires the interfacial electrical conductance to be within a range of values, and the thermal phonon conductance to be below a critical value. For the systems considered, these requirements on interface scattering for $ZT$ enhancement are expressed in terms of the bulk properties of the high-$ZT$ material, and the ratio of the constituent bulk $Z$ values.