Electrical transport and thermoelectric properties of PbTe1−xIx synthesized by high pressure and high temperature

N-type thermoelectric materials PbTe doped with iodine (PbTe1−xIx, x = 0.0001, 0.0003, 0.0007 and 0.001) were synthesized by high pressure and high temperature method (HPHT). Thermoelectric properties of PbTe1−xIx are investigated in the range of 300-600 K. The carrier concentration of PbTe prepared by HPHT is more sensitive to I content compared to that of the PbTe1−xIx sample prepared by other methods. The resistivities and the absolute values of Seebeck coefficients for PbTe1−xIx increase while the thermal conductivities decrease with increasing temperature. A large power factor of 39.1 μW/(cmK2) at room temperature is obtained with the carrier concentration of 9.7 × 1018 cm−3, which is much higher than that of Sb and Bi doped PbTe with the same synthesizing conditions. The high power factor is attributed to the high Hall mobility and large effective mass. The maximum figure-of-merit, ∼0.71 @ 600 K, is obtained for the samples with the carrier concentration of 9.7 × 1018 cm−3.