High Figure of Merit in Gallium-Doped Nanostructured n-Type PbTe- xGeTe with Midgap States

Zhong Zhen Luo, Songting Cai, Shiqiang Hao, Trevor P. Bailey, Xianli Su, Ioannis Spanopoulos, Ido Hadar, Gangjian Tan, Yubo Luo, Jianwei Xu, Ctirad Uher, Christopher Wolverton, Vinayak P. Dravid, Qingyu Yan*, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


PbTe-based thermoelectric materials are some of the most promising for converting heat into electricity, but their n-type versions still lag in performance the p-type ones. Here, we introduce midgap states and nanoscale precipitates using Ga-doping 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.

Original languageAmerican English
Pages (from-to)16169-16177
Number of pages9
JournalJournal of the American Chemical Society
Issue number40
StatePublished - 9 Oct 2019
Externally publishedYes

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Copyright © 2019 American Chemical Society.


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