Realizing Excellent Thermoelectric Performance of Sb₂Te₃ Based Segmented Leg with a Wide Temperature Range Using One-Step Sintering

To achieve a wide temperature range and a high figure-of-merit, segmented assembling is considered as the most effective method based on optimized low-temperature and medium-temperature thermoelectric materials. In this work, divalent magnesium (Mg) as acceptor doping in both Bi_0.5Sb_1.5Te₃ and indium (In) alloyed Sb₂Te₃ play an important role in improving thermoelectric performance, including enhanced power factor by balancing the electrical conductivity and Seebeck coefficient, reduced bipolar thermal conductivity by delaying occurrence of intrinsic excitation, and reduced lattice thermal conductivity due to point defects. Finally, both the figure-of-merit (ZT) value and the corresponding operating temperature range are improved. Typically, Mg_0.01Bi_0.5Sb_1.49Te₃ with a ZT_ave of 1.16 from 300 to 520 K and a ZT_ave of 0.84 for Mg_0.02In_0.1Sb_1.88Te₃ from 500 to 680 K are obtained. To further obtain wide-temperature high ZT value, p-type Mg_0.01Bi_0.5Sb_1.49Te₃/Mg_0.02In_0.1Sb_1.88Te₃ segmented leg with excellent interface bonding and extremely low contact resistivity is successfully fabricated by only one-step sintering process. The corresponding average ZT value is up to 1.02 with a broad temperature range from 300 to 680 K, and a maximum theoretical conversion efficiency of 12.7% with a temperature difference of 380 K is obtained. This provides guidelines for high efficiency thermoelectric devices.