All-Scale Hierarchically Structured p-Type PbSe Alloys with High Thermoelectric Performance Enabled by Improved Band Degeneracy
- Wuhan Univ. of Technology (China)
- Northwestern Univ., Evanston, IL (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
We show an example of hierarchically designing electronic bands of PbSe toward excellent thermoelectric performance. We find that alloying 15 mol % PbTe into PbSe causes a negligible change in the light and heavy valence band energy offsets (ΔEV) of PbSe around room temperature; however, with rising temperature it makes ΔEV decrease at a significantly higher rate than in PbSe. In other words, the temperature-induced valence band convergence of PbSe is accelerated by alloying with PbTe. On this basis, applying 3 mol % Cd substitution on the Pb sites of PbSe0.85Te0.15 decreases ΔEV and enhances the Seebeck coefficient at all temperatures. Here, excess Cd precipitates out as CdSe1-yTey, whose valence band aligns with that of the p-type Na-doped PbSe0.85Te0.15 matrix. This enables facile charge transport across the matrix/precipitate interfaces and retains the high carrier mobilities. Meanwhile, compared to PbSe the lattice thermal conductivity of PbSe0.85Te0.15 is significantly decreased to its amorphous limit of 0.5 W m-1 K-1. Consequently, a highest peak ZT of 1.7 at 900 K and a record high average ZT of ~1 (400-900 K) for a PbSe-based system are achieved in the composition Pb0.95Na0.02Cd0.03Se0.85Te0.15, which are ~70% and ~50% higher than those of Pb0.98Na0.02Se control sample, respectively.
- Research Organization:
- Northwestern Univ., Evanston, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); ONR; Natural Science Foundation of China
- Grant/Contract Number:
- SC0014520; N00014-18-1-2102; 11804261
- OSTI ID:
- 1777264
- Journal Information:
- Journal of the American Chemical Society, Vol. 141, Issue 10; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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