Thermoelectric Property Investigation of the PbTe Binary System with Doping

Lead telluride (PbTe) stands out as a significant thermoelectric material suitable for use in the intermediate temperature range. Nonetheless, the thermoelectric performance of n-type PbTe is constrained by its low figure of merit (zT). This investigation reveals a notable enhancement in the thermoelectric characteristics of PbTe alloys through strategic co-doping with trace amounts of bismuth (Bi) and iodine (I). The Pb1−xBixTe1−xIx alloys (x= 0.00%, 0.05%, 0.10%, 0.20%, and 0.50%) are synthesized through a systematic stepwise method. The incorporation of Bismuth and Iodine leads to an increase in carrier concentration while simultaneously lowering lattice thermal conductivity, attributed to heightened phonon scattering at grain boundaries and point defects. The maximum zT of 0.9 is attained at 725 K for the 0.20% co-doped sample, whereas the 0.05% co-doped sample shows the highest average zT (∼0.7) within the 323 K–723 K interval. The results indicate a direction for enhancing the thermoelectric efficiency of PbTe alloys, especially in n-type materials.