Synergistically promoted thermoelectric performance of SnTe by alloying with NaBiTe2

Abstract

SnTe, as a lead-free analog of PbTe, shows limited thermoelectric performance because of the high hole concentration arising from intrinsic Sn vacancies and its high thermal conductivity. Herein, we show a significantly improved thermoelectric performance in p-type SnTe through NaBiTe2 alloying, by which carrier concentration optimization, band structure engineering, and thermal conductivity reduction are simultaneously realized. Band modification is confirmed by transport coefficient analysis based on the single parabolic band model. The low lattice thermal conductivity of SnTe−NaBiTe2 solid solutions is ascribed to point defect scattering. As a result, a zT value of ∼1.1 at 834 K is achieved in the sample with the nominal composition of (SnTe)0.96(NaBiTe2)0.04.