Realizing high thermoelectric properties of SnTe via synergistic band engineering and structure engineering

Abstract Lead-free tin telluride (SnTe) has been drawn enormous attention recently due to their potential applications in the mid-temperature thermoelectric power generation. In this study, we systematically investigated the thermoelectric properties of In/Sr co-doped SnTe via first principles density functional theory calculation, coupled with extensive structural characterizations and property measurements. From which, we found that the co-doping of In and Sr in SnTe can significantly improve the electrical transport properties through unique interplay of band structure modifications, and the reduced lattice thermal conductivity can be achieved via strong phonon scattering by point defects, nanoprecipitates, and grain boundaries. Consequently, a record high power factor of ~33.88 μWcm−1K−2 and a peak figure of merit of ~1.31 have been achieved at 823 K for the Sn0.925In0.025Sr0.05Te pellet. This study indicates that In/Sr co-doping can effectively make incorporation of resonant levels, band degeneracy, band gap tuning and nanostructuring, leading to the achieving high thermoelectric performance of SnTe material.