Using Heterostructural Alloying to Tune the Structure and Properties of the Thermoelectric Sn1-xCaxSe

Bethany E. Matthews, Aaron M. Holder, Laura T. Schelhas, Sebastian Siol, James W. May, Michael R. Forkner, Derek Vigil-Fowler, Michael F. Toney, John D. Perkins, Brian P. Gorman, Andriy Zakutayev, Stephan Lany, Janet Tate

Research output: Contribution to journalArticlepeer-review

20 Scopus Citations

Abstract

We grow and kinetically stabilize the isotropic rocksalt phase of SnSe thin films by alloying SnSe with CaSe. Thin polycrystalline films of the metastable heterostructural alloy Sn1-xCaxSe are synthesized by pulsed laser deposition on amorphous SiO2 over the entire composition range 0 < x < 1. We observe the theoretically-predicted, composition-driven change from a layered, orthorhombic structure to an isotropic, cubic structure near x = 0.18, in reasonable agreement with the theoretical value of x = 0.13 calculated from first principles. The optical band gap is highly non-linear in x and the trend agrees with theory predictions. Compared to the layered end-member SnSe, the isotropic alloy near the orthorhombic-to-rocksalt transition has a p-type electrical resistivity three orders of magnitude lower, and a thermoelectric power factor at least ten times larger. Thus manipulation of the structure of a functional material like SnSe via alloying may provide a new path to enhanced functionality, in this case, improved thermoelectric performance.

Original languageAmerican English
Pages (from-to)16873-16882
Number of pages10
JournalJournal of Materials Chemistry A
Volume5
Issue number32
DOIs
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry 2017.

NREL Publication Number

  • NREL/JA-5K00-70057

Keywords

  • polycrystalline
  • thermoelectric performance
  • thin films

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