Achieving a High Average zT Value in Sb2Te3-Based Segmented Thermoelectric Materials.

A tiny amount of Mn is doped in In0.15Sb1.85Te3 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 zT value of Mn0.02In0.15Sb1.83Te3 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 Mn0.0075Bi0.5Sb1.4925Te3 previously reported by our group and using nickel as a barrier layer, a high average zT 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%.