High Thermoelectric Performance of Co-Doped Tin Telluride Due to Synergistic Effect of Magnesium and Indium

Abstract

Thermoelectric (TE) materials are considered go-to materials lately in addressing the worldwide energy crisis. We report a study on the effect of co-doping of magnesium and indium in lead-free SnTe both experimentally and theoretically. We show how the resonant levels introduced by indium increase the Seebeck coefficient at lower temperatures and how magnesium enhances the Seebeck at higher temperatures by opening the band gap and decreasing the energy difference between the light and heavy hole valence sub-bands. Synergistically, the effects of band engineering lead to the co-doped sample having high thermoelectric figure of merit (ZT) over a wide range of temperature and record a high power factor of ?42 ?W cm-1 K-2 for SnTe based materials. For the very first time we show the effect of site occupied by the dopant on the electronic structure of the material. The resulting high ZT of 1.5 at 840 K makes SnTe a very suitable material for thermoelectric applications. (Graph Presented). © 2017 American Chemical Society.