High-Performance p-Type Bi2Te3-Based Thermoelectric Materials with a Wide Temperature Range Obtained by Direct Sb Doping

Doping modification is one of the most effective ways to optimize the thermoelectric properties of Bi2Te3-based alloys. P-type Bi2-xSbxTe3 thermoelectric materials have been successfully prepared by direct Sb doping method. It can be found that doping Sb into Bi2Te3 lattice array for Bi-site replacement facilitates the generation of Sb '(Te) anti-site defects. This anti-site defects can increase the hole concentration and optimize electrical transport properties of Bi2-xSbxTe3 alloys. In addition, the point defects induced by mass and stress fluctuations and the Sb impurities produced during the sintering process can enhance the multi-scale phonon scattering and reduce the lattice thermal conductivity. As a result, the Bi0.47Sb1.63Te3 sample has a maximum thermoelectric figure of merit ZT of 1.04 at 350 K. It is worth noting that the bipolar effect of Bi2Te3-based alloys can be weakened with the increase of Sb content. The Bi0.44Sb1.66Te3 sample has a maximum average ZT value (0.93) in the temperature range of 300-500 K, indicating that direct doping of Sb can broaden the temperature range corresponding to the optimal ZT value. This work provides an idea for developing high-performance near room temperature thermoelectric materials with a wide temperature range.