Dopants effect on the band structure of PbTe thermoelectric material

PbTe is a promising thermoelectric material and its dimensionless figure of merit, zT, can be enhanced by optimizing the band structure near the Fermi level via chemical doping. This letter describes the dopants effect on bandgap, Eg, and effective mass, m*, for disordered La- and I-doping, based on theoretical calculations. Eg increases with increasing La and decreases with increasing I concentration. While m* increases upon La-doping, I-doping does not change m* noticeably. The calculated results are qualitatively consistent with the experimental results and explain the higher zT, up to 1.4 at 800 K, observed in I-doping PbTe compared to La-doping.