High Figure of Merit in Gallium-Doped Nanostructured n-Type PbTe-xGeTe with Midgap States.
J Am Chem Soc
; 141(40): 16169-16177, 2019 Oct 09.
Article
in En
| MEDLINE
| ID: mdl-31508945
ABSTRACT
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 (â¼0.65 W m-1 K-1 at 623 K). As a result, a high room-temperature thermoelectric figure of merit ZT â¼ 0.59 and a peak ZTmax of â¼1.47 at 673 K were obtained for the Pb0.98Ga0.02Te-5%GeTe. The ZTavg value that is most relevant for devices is â¼1.27 from 400 to 773 K, the highest recorded value for n-type PbTe.
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01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Am Chem Soc
Year:
2019
Document type:
Article
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