Enhancement of thermoelectric performance in n-type PbTe1-ySey by doping Cr and tuning Te:Se ratio

Lead telluride and its alloys have been extensively studied for medium temperature thermoelectric applications due to decent figure-of-merit (ZT) at temperature close to 900 K. However, little emphasis has been given to improve the ZT near room temperature. In this investigation, we report a systematic study of Cr doping in PbTe1-y Se-y with y=0, 0.25, 0.5, 0.75, 0.85, and 1. We found the peak ZT temperature increased with increasing concentration of Se. The highest ZT of similar to 0.6 at room temperature in Te-rich Cr0.015Pb3.985-Te0.75Se0.25 was obtained due to a lowered thermal conductivity and enhanced power factor resulted from high Seebeck coefficient of about -220 mu V K-1 and high Hall mobility similar to 1120 cm(2) V-1 s(-1) at room temperature. A room temperature ZT of 0.5 and peak ZT of 1 at about 573-673 K is shown by Se-rich sample Cr3.01Pb3.99Te0.25Se0.75. This improvement of the room temperature ZT improved the average ZT over a wide temperature range and could potentially lead to a single leg efficiency of thermoelectric conversion for Te-rich Cr0.015Pb0.985Te0.75Se0.25 up to 11% and Se-rich Cr0.01Pb0.99Te0.255Se0.75 up to 13% with cold side and hot side temperature at 300 K and 873 K, respectively, if matched with appropriate p-type legs. (C) 2015 Elsevier Ltd. All nghts reserved.