Abstract
PbSe is an attractive thermoelectric material due to its favorable electronic structure, high melting point, and lower cost compared to PbTe. Herein, the hitherto unexplored alloys of PbSe with NaSbSe2 (NaPbmSbSem+2) are described and the most promising p-type PbSe-based thermoelectrics are found among them. Surprisingly, it is observed that below 500 K, NaPbmSbSem+2 exhibits unorthodox semiconducting-like electrical conductivity, despite possessing degenerate carrier densities of ≈1020 cm−3. It is shown that the peculiar behavior derives from carrier scattering by the grain boundaries. It is further demonstrated that the high solubility of NaSbSe2 in PbSe augments both the thermoelectric properties while maintaining a rock salt structure. Namely, density functional theory calculations and photoemission spectroscopy demonstrate that introduction of NaSbSe2 lowers the energy separation between the L- and Σ-valence bands and enhances the power factors under 700 K. The crystallographic disorder of Na+, Pb2+, and Sb3+ moreover provides exceptionally strong point defect phonon scattering yielding low lattice thermal conductivities of 1–0.55 W m-1 K-1 between 400 and 873 K without nanostructures. As a consequence, NaPb10SbSe12 achieves maximum ZT ≈1.4 near 900 K when optimally doped. More importantly, NaPb10SbSe12 maintains high ZT across a broad temperature range, giving an estimated record ZTavg of ≈0.64 between 400 and 873 K, a significant improvement over existing p-type PbSe thermoelectrics.
Original language | English (US) |
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Article number | 1901377 |
Journal | Advanced Energy Materials |
Volume | 9 |
Issue number | 30 |
DOIs | |
State | Published - Aug 2019 |
Funding
This work was supported by the U.S. Department of Energy, Office of Science and Office of Basic Energy Sciences under award number DE-SC0014520-0003. This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois, through the IIN. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1324585. PYSA measurements were carried out with equipment acquired by ONR grant N00014-18-1-2102. This work was supported by the U.S. Department of Energy, Office of Science and Office of Basic Energy Sciences under award number DE-SC0014520-0003. This work made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois, through the IIN. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1324585. PYSA measurements were carried out with equipment acquired by ONR grant N00014-18-1-2102.
Keywords
- PbSe alloying
- band structure engineering
- grain boundary charge transport
- low thermal conductivity
- thermoelectric materials
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science