Atomic disordering advances thermoelectric group IV telluride alloys with a multiband transport

Abstract

Minimization of lattice thermal conductivity plays a key role in advancing thermoelectrics, a typical strategy of which is the introduction of atomic disorder for strong phonon scattering through atomic mass and strain fluctuations. Maximizing this type of scattering requires dense point defects with large mass/strain contrasts, motivating the current work to focus on the thermoelectric properties of Sn1/3Ge1/3Pb1/3Te with massive disordered cations. Thanks to the formation of a solid solution around this particular composition, which enables an atomic disorder significantly higher than ever reported in IV-VI alloys, the resultant strong phonon scattering leads to a dramatic reduction in lattice thermal conductivity in the entire temperature range. In addition, MnTe alloying leads to a maximization of transporting valence bands for a superior electronic performance. These effects end up with both an extraordinary peak figure of merit and a significant improvement in its average. This leads Sn1/3Ge1/3Pb1/3Te alloys, crystallographically close relatives to SnTe, to be significantly superior in thermoelectric performance to that of SnTe.