Abstract
Here we report that CdTe alloying and Sb doping increase the density-of-states effective mass and introduce endotaxial nanostructuring in n-type PbTe, resulting in enhanced thermoelectric performance. A prior theoretical prediction for the presence of resonance states in the conduction band of this system, however, could not be confirmed. An amount of 3 mol % CdTe alloying widens the band gap of PbTe by 50%, leading to enhanced carrier effective mass and Seebeck coefficient. This effect is even more pronounced at high temperatures where the solubility of CdTe increases. At 800 K, when the carrier concentration is the same (4 × 10 19 cm -3 ), the Seebeck coefficient of CdTe-alloyed PbTe is -195 μV K -1 , 16% higher than that of the Cd-free control sample (-168 μV K -1 ). Sb doping considerably increases the electron concentration of Pb 0.97 Cd 0.03 Te, giving rise to optimized power factors of ∼17 μW cm -1 K -2 at 800 K. More importantly, Sb induces strained endotaxial nanostructures evenly distributed in the matrix. These Sb-rich nanostructures account for the ∼40% reduction in the lattice thermal conductivity over the whole measured temperature range. As a result, a maximum ZT of 1.2 is attained at 750 K in 0.5 mol % Sb-doped Pb 0.97 Cd 0.03 Te alloys.
Original language | English (US) |
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Pages (from-to) | 9197-9204 |
Number of pages | 8 |
Journal | ACS Applied Materials and Interfaces |
Volume | 11 |
Issue number | 9 |
DOIs | |
State | Published - Mar 6 2019 |
Funding
G.T. acknowledges the financial support from the Natural Science Foundation of China (Grant 11804261). At North- western University the work was supported primarily by the Department of Energy, Office of Science, Basic Energy Sciences under Grant DE-SC0014520 (synthesis, sample processing, transport, TEM and DFT calculations). Transmission electron microscopy work was partially performed in the EPIC facility of the NUANCE Center at Northwestern University. Access to facilities of high performance computational resources at the Northwestern University is acknowledged.
Keywords
- electronic structure
- lead telluride
- nanostructuring
- thermal conductivity
- thermoelectric
ASJC Scopus subject areas
- General Materials Science