Thermoelectric performance of p-type zone-melted Se-doped Bi_0.5Sb_1.5Te₃ alloys

For zone-melted (ZM) bismuth telluride-based alloys, which are widely commercially available for solid-state cooling and low-temperature power generation around room temperature, introducing point defects is the chief approach to improve their thermoelectric performance. Herein, we report the multiple effects of Se doping on thermoelectric performance of p-type Bi_0.5Sb_1.5Te_3-xSe _x + 3 wt% Te ZM ingots, which increases carrier concentration, reduces lattice thermal conductivity and deteriorates the carrier mobility. As a result, the peak figure of merit (ZT) is shifted to a higher temperature and a high ZT ~ 1.2 at 350 K is obtained, due to the reduced thermal conductivity and suppressed intrinsic conduction. Further, decreasing Sb content is followed to optimize the room temperature performance and a ZT ~ 1.1 at 300 K is obtained. These results are significant for designing and optimizing the thermoelectric performance of commercial Bi_0.5Sb_1.5Te₃+ 3 wt% Te ZM alloys.