The role of ionized impurity scattering on the thermoelectric performances of rock salt AgPbmSnSe2+m

TL;DR

This study demonstrates how ionized impurity scattering influences and enhances the thermoelectric performance of AgPbmSnSe2+m by optimizing electrical and thermal transport properties, achieving a ZT of 1.3 at high temperature.

Contribution

It reveals the role of ionized impurity scattering in improving thermoelectric efficiency in rock salt AgPbmSnSe2+m, providing a new approach for material optimization.

Findings

ZT reaches 1.3 at 889 K for m=50

Ionized impurity scattering enhances Seebeck coefficient

Thermal conductivity is reduced by suppressing bipolar effects

Abstract

We report on the successful synthesis and on the properties of polycrystalline AgPbmSnSe2+m (m = ++++, 100, 50, 25) samples with a rock salt structure. Between 160 K and 400 K, the dominant scattering process of the carriers in this system changes from acoustic phonon scattering in PbSe to ionized impurity scattering in AgPbmSnSe2+m, which synergistically optimizes electrical and thermal transport properties. Thanks to the faint amount of AgSnSe2, the Seebeck coefficient is enhanced by boosting the scattering factor, the electric conductivity is improved by the increase of the concentration of holes coupled to a limited degradation of their mobility, and the total thermal conductivity is reduced by suppressing bipolar thermal conductivity. Therefore, ZT of AgPbmSnSe2+m (m = 50) reaches 1.3 at 889 K. The mechanism suggested in this study opens new paths to improve the thermoelectric performances of other families of materials.