Development of p-type Bi_2−xSb_xTe₃ thermoelectric materials for power generation application exploiting synergetic effect of Sb alloying and repress process

Bi–Te based alloy compounds are currently the best-performing thermoelectric materials near room temperature. However, with the temperature increase, their conversion efficiency drops dramatically due to intrinsic excitation, thereby limiting their power generation application. In this study, for low-temperature thermoelectric power generation, we develop p-type Bi–Sb–Te alloys with the highest performance at a temperature of ~473 K. Here, we note that increasing the amount of Sb can effectively suppress intrinsic excitation, shifting the ZT peak towards higher temperatures. Moreover, we apply the repress process, through which microstructures such as grain boundaries and dislocations are developed in the material, which in turn reduces the thermal conductivity. As a result, a peak ZT of ~1.32 at 473 K is achieved for Bi_0.3Sb_1.7Te₃ in the direction parallel to the pressure, which indicates its large application prospect for low-temperature thermoelectric power generation.