TY - JOUR
T1 - High Figure of Merit in Gallium-Doped Nanostructured n-Type PbTe- xGeTe with Midgap States
AU - Luo, Zhong Zhen
AU - Cai, Songting
AU - Hao, Shiqiang
AU - Bailey, Trevor P.
AU - Su, Xianli
AU - Spanopoulos, Ioannis
AU - Hadar, Ido
AU - Tan, Gangjian
AU - Luo, Yubo
AU - Xu, Jianwei
AU - Uher, Ctirad
AU - Wolverton, Christopher
AU - Dravid, Vinayak P.
AU - Yan, Qingyu
AU - Kanatzidis, Mercouri G.
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/10/9
Y1 - 2019/10/9
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85072924921&partnerID=8YFLogxK
U2 - 10.1021/jacs.9b09249
DO - 10.1021/jacs.9b09249
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C2 - 31508945
AN - SCOPUS:85072924921
SN - 0002-7863
VL - 141
SP - 16169
EP - 16177
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 40
ER -
