All-Scale Hierarchically Structured p-Type PbSe Alloys with High Thermoelectric Performance Enabled by Improved Band Degeneracy

Gangjian Tan*, Shiqiang Hao, Songting Cai, Trevor P. Bailey, Zhongzhen Luo, Ido Hadar, Ctirad Uher, Vinayak P. Dravid, Christopher Wolverton, Mercouri G. Kanatzidis

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

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. 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.

Original languageEnglish (US)
Pages (from-to)4480-4486
Number of pages7
JournalJournal of the American Chemical Society
Volume141
Issue number10
DOIs
StatePublished - Mar 13 2019

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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