Multiple effects result in significantly improved thermoelectric figure-of-merit of InSb semiconductors via embedding metastable Ag/Pt nano particles

Abstract

InSb-based semiconductors are potential thermoelectric (TE) materials in the medium temperature range due to their non-toxicity, abundance, excellent process compatibility and stable chemical properties. The mobility of pure InSb is as high as 104–105 cm2 V−1 s−1, which results in the ultra-high power factor (PF). However, the lattice thermal conductivity (κl) is also high because of the intrinsic strong chemical bonding, resulting in a low zT value (∼0.38, at 773 K). In this study, a feasible strategy was adopted to decrease the κl of InSb by embedding Ag/Pt nano particles (NPs) into the InSb bulks. The κl at 703 K was reduced to 2.37 W m−1 K−1 (decrease by ∼40.3%) on account of the enhanced phonon scattering after embedding 2.0% Ag/Pt NPs. Moreover, owing to the synergistic optimization of element doping and energy filtering effects, the PF at 703 K was improved to 5.66 × 10−3 W m−1 K−2 in the InSb+2.0% Ag/Pt NPs sample, which is ∼63.1% higher than that of pristine InSb (3.47 × 10−3 W m−1 K−2). Ultimately, a remarkably high zT value of 0.81 was achieved at 703 K in the InSb+2.0% Ag/Pt NPs sample, which is ∼92.9% higher than that of the pure InSb. Embedding metastable NPs to achieve multiple effects simultaneously, including the phonon scattering, element doping and energy filtering effects is a feasible means to enhance the zT values, which probably is applicable to other TE materials.