%0 Journal Article
%T High Thermoelectric Performance in SnTe每AgSbTe2 Alloys from Lattice Softening, Giant Phonon每Vacancy Scattering, and Valence Band Convergence
%J -
%D 2018
%R https://doi.org/10.1021/acsenergylett.8b00137
%X We report on the underlying mechanism that enables the SnTe每AgSbTe2 system to exhibit superior thermoelectric figure of merit (ZT) compared to its parent compound SnTe. We show that AgSbTe2 alloying has a profound impact on the band structure of SnTe by converging the energies of its light and heavy valence bands, leading to significantly enhanced Seebeck coefficients. We have also unraveled a significant connection between alloying and defect stability in this system, wherein the Sn vacancy concentration increases significantly when Ag and Sb are alloyed on the Sn site. The increased Sn vacancy concentration dramatically reduces the lattice thermal conductivity through both lattice softening and phonon每vacancy scattering to ‵0.4 W m每1 K每1 at 800 K. Consequently, a ZT value of 1.2 at 800 K for AgSn5SbTe7 can be achieved by doping I on Te sites. This represents a 300% improvement over pristine SnTe, outperforming many reported SnTe-based thermoelectric materials
%U https://pubs.acs.org/doi/10.1021/acsenergylett.8b00137