High-Performance p-Type Bi₂Te₃-Based Thermoelectric Materials Enabled via Regulating Bi-Te Ratio

Bi₂Te₃-based alloys, as the sole commercial thermoelectric (TE) material, play an irreplaceable role in the thermoelectric field. However, the low TE efficiency, poor mechanical properties, and high cost have limited its large-scale applications. Here, high-performance p-type Bi₂Te₃-based materials were successfully prepared by ball milling and hot pressing. The optimized p-type Bi_0.55Sb_1.45Te₃ + 2.5 wt % Bi shows a peak zT value of 1.45 at 360 K, and the average zT value of up to 1.24 at 300-480 K, which is completely comparable with previously reported Bi₂Te₃-based alloys with excellent performance. Such performance mainly results from the enhanced electrical conductivity and decreased lattice thermal conductivity via regulating carrier and phonon transport. Furthermore, this material shows good mechanical properties, in which the Vickers hardness and compressive strength are up to 0.95 GPa and 94.6 MPa, respectively. Overall, both the thermoelectric and mechanical performance of the materials fabricated by our processing technology are quite competitive. This may enlighten researchers concentrating on Bi₂Te₃-based alloys, thus further promoting their industrial applications.