Manipulating the Solubility of SnSe in SnTe by Br Doping for Improving the Thermoelectric Performance

As a potential thermoelectric (TE) candidate with a rock salt structure similar to PbTe, SnTe has attracted much attention in recent years. However, a high carrier concentration caused by its inherent Sn vacancy severely lowers the TE performance. In this study, it is found that the introduction of Br on the basis of Se doping not only manipulates the carrier concentration but also reduces the solubility of SnSe in SnTe to form SnSe nanoprecipitates with suitable sizes (<10 nm) to scatter phonons. Thereby, the power factor is improved (∼1943 μW m–1 K–2) and the thermal conductivity is reduced (∼2.13 W m–1 K–1), pushing the zT value up to ∼0.75 (Sn1.03Se0.12Te0.870Br0.010) at 823 K. This study combines the carrier and chemical solubility engineering by halogen doping and provides an approach to improve the TE performance of materials with similar structures.