Enhanced thermoelectric performance of p-type sintered BiSbTe-based composites with AgSbTe2 addition

Abstract Bismuth telluride-based materials have been widely used in the field of thermoelectric cooling near room temperature. However, the material utilization and device conversion efficiency were limited by the low thermoelectric performance and poor mechanical properties of commercial zone-melting materials. With an aim to optimize the comprehensive properties, we prepared the composite samples of Bi0.48Sb1.52Te3 (BST)-x wt% AgSbTe2 (x = 0, 0.05, 0.1, 0.2) via the hot pressing method. It was found that the AgSbTe2 addition can effectively increase the carrier concentration and improve the power factor to 46 μW cm−1 K−2 at 300 K. Due to the introduction of dislocations, stress and Te inhomogeneities, the lattice thermal conductivity of the composite was significantly reduced to 0.69 W m−1 K−1 at 325 K. As a result, a maximum ZT of 1.15 at 325 K is obtained for the x = 0.1 sample. Interestingly, BST-0.1 wt% AgSbTe2 exhibits roughly isotropic thermoelectric performance perpendicular to and parallel to the pressing direction. Our study suggests that the BST-AgSbTe2 composite is very promising for the application of thermoelectric refrigeration near room temperature.