Modulation of BixSb2−xTe3 Alloy Application Temperature via Optimizing Material Composition

Bi₂Te₃-based alloys are representatively commercialized thermoelectric materials for refrigeration and power generation. Refrigeration mainly utilizes thermoelectric properties near room temperature, while the power generation temperature is relatively high. However, it is difficult for bismuth telluride to maintain good thermoelectric properties throughout the entire temperature range of 300-500 K. Herein, a series of Bi<i>_x</i>Sb_2-<i>x</i>Te₃ alloys with different Bi contents were prepared by a simple preparation method and systematically investigated, and their best application temperature range was found. The Bi content can modulate carrier concentration and band gap, and the maximum dimensionless figure of merit (<i>ZT</i>) value of Bi<i>_x</i>Sb_2-<i>x</i>Te₃ can be achieved in the corresponding application temperature range. The maximum <i>ZT</i> of Bi_0.3Sb_1.7Te₃ with a Bi content equal to 0.3 reaches 1.14 at 400 K, and the average <i>ZT</i> is 1.06 in the range of 300-500 K, which is suitable for both power generation and refrigeration. Therefore, power generation technologies with higher application temperatures should be selected from Bi<i>_x</i>Sb_2-<i>x</i>Te₃ materials with Bi content less than 0.3, and refrigeration technologies with lower application temperatures should be selected with Bi content greater than 0.3. This work provides experimental guidance for finding the composition of Bi₂Te₃-based alloys in scientific research and practical applications.