Boosting the Thermoelectric Performance of SnTe through Localized van der Waals Gaps construction and Configurational-Entropy Engineering

Abstract

SnTe, as an environmentally friendly lead-free p-type thermoelectric material, is deemed of potential applications in the medium temperature range (500-900 K); however, the thermoelectric performance of SnTe material is limited by its intrinsic characters such as the small formation energy of Sn vacancy, the low degeneracy of valence bands, and relatively high lattice thermal conductivity. In this study, we begin with alloying non-stoichiometric Ag 1-δ Sb 1+δ Te 2+δ to constructing localized van der Waals (vdWs) planar gaps for reduced lattice thermal conductivity, configurational entropy engineering is then adopted to optimize its valence band structure. Increased configurational entropy simultaneously aggravates lattice distortion, which further helps reducing the lattice thermal conductivity. Ultimately, we achieved a decent maximal figure of merit ZT ~ 1.23 at 623 K and an outstanding average ZT ~ 0.96 in the 323-823 K temperature range; remarkably, the room-temperature ZT reaches as high as ~ 0.38, which is one the highest values reported so far. The findings in this study might shed light on future researches on SnTe and related material systems.