Abstract
SnTe is a promising alternative of the toxic PbTe, but the concepts of band engineering and thermoelectric performance optimization are restricted by the low solid solubility of effective dopants. Here, we demonstrate a raised Mn solubility limit of around 15% in the SnTe-GeMnTe2 medium-entropy system. Density functional theory calculations show that high doping fraction of Mn gives rise to a near-complete valence band convergence that is responsible for the obviously improved Seebeck coefficient. High-content GeMnTe2 alloying also profoundly creates multiscale microstructure for an extreme low lattice thermal conductivity. These effects yield a high ZTmax of 1.4 at 850 K and a record Vickers hardness of 1.65 GPa in (Sn0.96Sb0.04Te)0.7(Ge0.5Mn0.5Te)0.3. Stem from excellent thermoelectric and mechanical properties, the fabricated thermoelectric module comprised of our p-type SnTe exhibits a conversion efficiency of 6.1% and an output power density of 0.43 W cm–2 under a temperature gradient of 350 °C. This study opens the door for the development of SnTe-based modules, which is promising for the low-grade heat harvest at mid-low temperature.
Published Version
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