Arrays of planar vacancies in superior thermoelectric Ge1−x−yCdxBiyTe with band convergence

Hong, Min and Wang, Yuan and Liu, Weidi and Matsumura, Syo and Wang, Hao and Zou, Jin and Chen, Zhi-Gang (2018) Arrays of planar vacancies in superior thermoelectric Ge1−x−yCdxBiyTe with band convergence. Advanced Energy Materials, 8 (30 - Article 1801837). ISSN 1614-6832

Abstract

The multivalence bands in GeTe provide an additional handle to manipulate the thermoelectric performance. Herein, the density‐functional‐theory calculation indicates that Cd doping enables the convergence of these multivalence bands. Plus, the additional Bi dopant serving as the electron donors optimizes the carrier concentration, leading to an enhanced power‐factor in Ge1−x−yCdxBiyTe. Moreover, comprehensive electron microscopy characterizations demonstrate the array of high‐density planar vacancies in Ge1−x−yCdxBiyTe stemming from the absence of {111} Ge atomic planes, which is driven by the reduced formation energy in the scenario of Cd/Bi codoping. Simulations of phonon transport confirm the significant role of planar vacancies in scattering mid‐frequency phonons. Such high‐density planar vacancies, in tandem with grain boundaries and point defects, lead to a lattice thermal conductivity of 0.4 W m−1 K−1 in Ge1−x−yCdxBiyTe, reaching the amorphous limit. Ultimately, a peak zT of 2.2 is realized, which promotes GeTe into the first echelon of cutting‐edge thermoelectric materials. The strategy of combining band convergence and planar vacancies opens an avenue to develop Pb‐free derivatives with superhigh thermoelectric efficiency.


Statistics for USQ ePrint 35503
Statistics for this ePrint Item
Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty / Department / School: No Faculty
Date Deposited: 08 Feb 2019 01:34
Last Modified: 04 Mar 2019 01:36
Uncontrolled Keywords: band convergence, GeTe alloys, high-performance thermoelectrics, planar vacancies, TEM characterizations
Fields of Research : 09 Engineering > 0912 Materials Engineering > 091205 Functional Materials
Funding Details:
Identification Number or DOI: 10.1002/aenm.201801837
URI: http://eprints.usq.edu.au/id/eprint/35503

Actions (login required)

View Item Archive Repository Staff Only