Band and scattering tuning for high performance thermoelectric Sn1−xMnxTe alloys

Abstract

The thermoelectric figure of merit zT of SnTe, an analogue to PbTe, has long been known to be about 0.6, mainly due to its single band transport behavior. Similar to what has been found in PbTe, alloying with group II monotellurides such as CdTe, HgTe, MgTe enables a reduced energy separation between the two valence bands of SnTe, leading to converged bands for a significantly increased zT to ∼1.1 with demonstrated further improvements by other independent strategies such as nanostructuring. Here we show alloying with highly soluble MnTe not only tunes the band structure but also reduces the lattice thermal conductivity, leading to a record zT of ∼1.3 at 900 K in the alloy form that does not rely on additional mechanisms for lattice thermal conductivity reduction. This work demonstrates Sn1−xMnxTe as a potential alternative for PbTe with toxic Pb.