Low-cost p-type Bi2Te2.7Se0.3 zone-melted thermoelectric materials for solid-state refrigeration

Abstract

Bismuth-telluride-based solid solutions are the unique thermoelectric (TE) materials near room temperature and the commercial ingots are usually grown by zone melting (ZM) method. The traditional p-type composition used for solid-state refrigeration is Bi0.5Sb1.5Te3 + x wt% Te, while the relatively high lattice thermal conductivity hinders the further enhancement of zT values and the high prices of Sb and Te increase the cost of large-scale commercial applications. Herein, the TE properties of p-type Bi2-xSbxTe2.7Se0.3 ZM ingots are investigated systematically. Attributed to the synergistic role of decreased lattice thermal conductivity and optimized carrier concentration, a peak zT ∼1.05 is obtained in Bi1.5Sb0.5Te2.7Se0.3 around 330 K, which is comparable to the typical p-type Bi0.5Sb1.5Te3 + x wt% Te ZM ingots. Furthermore, the cost decreases by ∼10% due to the lower contents of Sb and Te. The comparable zT and lower cost are advantageous to TE industry and demonstrate the potential of Bi2Te3-Sb2Te3-Bi2Se3 quasi-ternary solid solutions.