Influence of Biaxial and Isotropic Strain on The Thermoelectric Performance of PbSnTeSe High-Entropy Alloy: A Density-Functional Theory Study

Abstract

Strain engineering is an effective method to improve materials thermoelectric (TE) performance. In this study, both biaxial and isotropic strains ranging from -3% to +3% and from -3% to -1%, respectively, were applied to improve the TE properties of PbSnTeSe high entropy alloy (HEA). The effects of strain on the TE transport properties of PbSnTeSe HEA were investigated using first-principles calculations combined with Boltzmann transport theory. Under biaxial strain, n-type doped PbSnTeSe HEA shows an increase in the optimal power factor ($$) with both compressive and tensile strains. For p-type doping, compressive strain enhances the $$, whereas tensile strain reduces it. Within a strain range of -3% to +3%, the optimal $$ are 7.8–9.5 mW/mK² for n-type and 0.85–1.3 mW/mK² for p-type doped PbSnTeSe HEA. The maximum figure of merit ($$) value of 1.63 for n-type doped PbSnTeSe HEA at 300 K under 3% tensile strain is 61% higher than the $$ value of 1.1 without strain. Under isotropic strain ranging from 0% to -3%, the $$ increases from 7.8 to 14 mW/mK² for n-type and from 1.1 to 3.4 mW/mK² for p-type doped PbSnTeSe HEA. Additionally, isotropic strain boosts the maximum $$ value for p-type doped PbSnTeSe HEA at 300 K from 0.3 to 0.85 under -3% strain. This study confirms that strain engineering is an effective strategy to enhance the thermoelectric properties of PbSnTeSe HEA.