Boosting the Thermoelectric Performance of Pseudo-Layered Sb2Te3(GeTe) n via Vacancy Engineering

Xiao Xu; Lin Xie; Qing Lou; Di Wu; Jiaqing He

doi:10.1002/advs.201801514

Boosting the Thermoelectric Performance of Pseudo-Layered Sb₂Te₃(GeTe) _n via Vacancy Engineering

Adv Sci (Weinh). 2018 Oct 12;5(12):1801514. doi: 10.1002/advs.201801514. eCollection 2018 Dec.

Authors

Xiao Xu¹, Lin Xie¹, Qing Lou¹, Di Wu^{1

2}, Jiaqing He¹

Affiliations

¹ Shenzhen Key Laboratory of Thermoelectric Materials Department of Physics Southern University of Science and Technology Shenzhen 518055 China.
² School of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 China.

Abstract

An ultrahigh figure of merit ZT value ≈2.4 at 773 K for p-type pseudo-layered Sb₂Te₃(GeTe)₁₇ along the parallel direction is reported by synergistically optimizing its electrical and thermal properties via vacancy engineering. The microstructural origin of thermoelectric property enhancement is studied by spherical aberration corrected transmission electron microscopy and its in situ mode. The results reveal that upon annealing, Ge vacancy gaps in quenched samples tend to migrate and recombine into long-range gaps in order to minimize the elastic and electrostatic energies. The recombination of Ge gaps would lead to an overall reduction of carrier concentration and electrical thermal conductivity. The detailed study of Ge vacancies migration via heat treatment and its effects on thermoelectric performance in pseudo-layered Sb₂Te₃(GeTe)₁₇ materials can provide enlightening clues for future research in a number of thermoelectric materials of similar structures.

Keywords: Sb2Te3(GeTe)n; in situ TEM; thermoelectric properties; vacancy engineering.