Improvements of the thermoelectric properties of PbTe via simultaneous doping with indium and iodine

The thermoelectric properties of n-type InxPb1−xTe1−yIy (with x = 0.005, 0.01, 0.015; y = 0.001, 0.002, 0.004, 0.006) were investigated at elevated temperatures up to 655 K. This co-doping significantly affected the Seebeck coefficient and electrical conductivity of all samples within the measured temperature regime except for the sample with the largest concentration of In, wherein the effects of I-doping are comparatively minor. For a given concentration of In, the sample with the largest amount of iodine possesses the highest electrical conductivity, which is consistent within all three sets of samples in our present study. Thermal conductivity values are generally lower than those of undoped PbTe. An increasing iodine concentration at fixed In content was found to gradually increase the dimensionless figure-of-merit, ZT, an effect most significantly observed when x = 0.01.