Evaluation on the Thermoelectric Cooling Ability of PbTe

High thermoelectric cooling efficiency requires a high average ZT value, especially in a low temperature range. PbTe-based compounds are typical intermediate-temperature thermoelectric materials due to their relatively low ZT values near room temperature. Here, we attempt to enhance the average ZT value of PbTe, especially at 300-600 K, through decreasing its band gap so as to evaluate the thermoelectric cooling performance. The results show that Sn alloying in PbTe can narrow its band gap from ∼0.28 to ∼0.18 eV, which shifts its peak power factor from 673 to 523 K. Combining the enhanced power factor with the reduced lattice thermal conductivity after Sn alloying, a maximum average ZT value of ∼0.74 is obtained in n-type Pb0.785Sn0.2Sb0.015Te at 300-723 K. Finally, the thermoelectric cooling performance of a Pb0.785Sn0.2Sb0.015Te-based single leg is measured, and a cooling ΔTmax of ∼15 K is realized. These results demonstrate that, after tuning the band gap, PbTe can also exhibit promising cooling performance even though it is a typical intermediate-temperature thermoelectric material.