Structural, Electronic and Thermoelectric Properties of Pb1−xSnxTe Alloys

Abstract

The structural, electronic and thermoelectric properties of Pb1−xSnxTe (x = 0, 0.25, 0.5, 0.75, 1) alloys are investigated using density functional theory and the semi-classical Boltzmann transport theory. Both PbTe and SnTe binary alloys exhibit a semiconducting behavior with narrow direct bandgaps of 0.114 eV and 0.107 eV, respectively, at the L high-symmetry point. However, the alloying of Sn over Pb in PbTe alloy shows diverse electronic properties from a zero bandgap to 0.0833 eV depending upon the Pb/Sn concentrations. The p-type of PbTe is found to have a maximum Seebeck coefficient of 343.14 μV/K at 300 K, whereas the n-type of SnTe shows a peak of 246.32 μV/K at 300 K. The p-type of PbTe and n-type of SnTe exhibit the highest power factors of 119.76 × 10−3 Wm−1 K−2 and 148.32 × 10−3 Wm−1 K−2, respectively, at 900 K among all Pb1−xSnxTe alloys. However, Pb0.5Sn0.5Te alloy also shows a reasonably significant Seebeck coefficient and power factor for both the p- and n-type dopings. The interesting thermoelectric properties of these Pb1−xSnxTe alloys show high potential towards high thermoelectric efficiency and device applications.