Achieving a High Average <i>zT</i> Value in Sb₂Te₃-Based Segmented Thermoelectric Materials

Abstract

A tiny amount of Mn is doped in In_0.15Sb_1.85Te₃ sample to tailor its carrier concentration, thus boosting the power factor and suppressing the bipolar effect. Furthermore, large amounts of nanotwins are constructed to effectively scatter the phonons and reduce the lattice thermal conductivity. As a result, the <i>zT</i> value of Mn_0.02In_0.15Sb_1.83Te₃ is enhanced up to 1.0 at 673 K, making this material a robust candidate for medium-temperature (500-673 K) thermoelectric applications. Then combining with the low-temperature thermoelectric material Mn_0.0075Bi_0.5Sb_1.4925Te₃ previously reported by our group and using nickel as a barrier layer, a high average <i>zT</i> value of 1.08 during a broad temperature range from 303 to 673 K together with an Ohmic contact interface bonding is achieved in the p-type segmented leg fabricated via simple one-step sintering. Finally, the maximum theoretical conversion efficiency with a temperature difference of 370 K reaches ∼12.7%.