Constructing van der Waals gaps in cubic-structured SnTe-based thermoelectric materials

Abstract

The practical application of eco-friendly tin telluride (SnTe) at intermediate temperatures has been long restricted by its lower average ZT than that of state-of-art PbTe. Here, a maximal figure of merit ZT_max ∼ 1.4 at 773 K and an ultrahigh ZT_ave ∼ 0.83 (between 323 and 773 K) are realized in SnTe by alloying with Sb₂Te₃ and follow-up rhenium doping. Microstructural characterizations reveal that Sb₂Te₃ alloying produces van der Waals gap-like structure throughout the SnTe matrix, leading to a significant reduction of lattice thermal conductivity; rhenium doping can tune the carrier concentration precisely at high temperatures, thus further improving the power factor. The construction of gap-like structure in our Sb₂Te₃(SnTe)_n samples and its remarkable effect on thermoelectric transports can shed light for future studies of SnTe and analogous thermoelectric systems.