High thermoelectric performance in p-type InSb with all-scale hierarchical architectures

Abstract

We realize the switch of InSb from its intrinsic n-type to p-type semiconductor nature through the substitution of Zn for In. Then, to reduce the high thermal conductivity of p-type InSb, MnO2 is added into p-type InSb matrix. A solid reaction between the MnO2 additives and InSb matrix takes place during spark plasma sintering process. By this approach, the point defect MnIn+, nanoscale In2O3 precipitates, and microscale MnO2 and Sb secondary phases are formed in InSb. Such all-scale hierarchical architectures play a critical role in the suppression of phonon transport, realizing a low lattice thermal conductivity of 1.50 W/m/K at 733 K for Zn0.04In0.96Sb + 3 wt.% MnO2, 58% lower than that of ZnxIn1-xSb. Meanwhile, the Zn0.04In0.96Sb + 3 wt.% MnO2 maintains excellent electrical properties (i.e., power factor ∼ 21 μW/cm/K2 at 733 K). Eventually, the thermoelectric figure of merit ZT of Zn0.04In0.96Sb + 3 wt.% MnO2 material reaches 0.54 at 733 K, which is comparable to the well-established peak ZT of n-type InSb at the same temperature, showing promising potential in thermoelectric power generation.