Band and vacancy engineering in SnTe to improve its thermoelectric performance

SnTe is a promising thermoelectric material with low cost and high stability. However, its performance is limited by the large energy separation between the light hole L band and the lower, heavy hole sigma band. Despite the efforts being made to induce band convergence, the improvements are very limited. In this work, the band flattening was first induced by Sb2Te3 alloying, which increases the density of states effective mass of the L band by 278%. The carrier mobility and lattice thermal conductivity were subsequently optimized through vacancy defect manipulation via Pb compensation. Eventually, a peak zT of 1.1 at 778 K and an average zT of 0.56 from 300 K to 778 K is achieved in (Sn0.98Ge0.05Te)0.91(Sb2Pb0.5Te3)0.09, which is one of the best SnTe-based thermoelectric systems. SnTe is a promising thermoelectric material with low cost and high stability.