High Figure of Merit in Gallium-Doped Nanostructured n-Type PbTe-xGeTe with Midgap States
Journal Article
·
· Journal of the American Chemical Society
- Nanyang Technological Univ. (Singapore); Northwestern Univ., Evanston, IL (United States); Northwestern University
- Northwestern Univ., Evanston, IL (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Wuhan Univ. of Technology, Wuhan (China)
- Nanyang Technological Univ. (Singapore); Northwestern Univ., Evanston, IL (United States)
- Agency for Science, Technology and Research (A*STAR), Innovis (Singapore). Institute of Materials Research and Engineering
- Nanyang Technological Univ. (Singapore)
PbTe-based thermoelectric materials are some of the most promising for converting heat into electricity, but their ntype versions still lag in performance the p-type ones. Here, we introduce midgap states and nanoscale precipitates using Gadoping and GeTe-alloying to considerably improve the performance of n-type PbTe. The GeTe alloying significantly enlarges the energy band gap of PbTe and subsequent Ga doping introduces special midgap states that lead to an increased density of states (DOS) effective mass and enhanced Seebeck coefficients. Moreover, the nucleated Ga2Te3 nanoscale precipitates and off-center discordant Ge atoms in the PbTe matrix cause intense phonon scattering, strongly reducing the thermal conductivity (~0.65 W m-1 K-1 at 623 K). As a result, a high room-temperature thermoelectric figure of merit ZT ~ 0.59 and a peak ZTmax of ~1.47 at 673 K were obtained for the Pb0.98Ga0.02Te-5%GeTe. The ZTavg value that is most relevant for devices is ~1.27 from 400 to 773 K, the highest recorded value for n-type PbTe.
- Research Organization:
- Northwestern Univ., Evanston, IL (United States)
- Sponsoring Organization:
- National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231; AC02-06CH11357; SC0014520
- OSTI ID:
- 1776870
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 40 Vol. 141; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Influence of Nanostructuration on PbTe Alloys Synthesized by Arc-Melting
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journal | November 2019 |
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