Polycrystalline SnSe with a thermoelectric figure of merit greater than the single crystal

Chongjian Zhou, Yong Kyu Lee, Yuan Yu, Sejin Byun, Zhong Zhen Luo, Hyungseok Lee, Bangzhi Ge, Yea Lee Lee, Xinqi Chen, Ji Yeong Lee, Oana Cojocaru-Mirédin, Hyunju Chang, Jino Im, Sung Pyo Cho, Matthias Wuttig, Vinayak P. Dravid, Mercouri G. Kanatzidis, In Chung*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Thermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2–2.6 at 913 K, but more practical and deployable polycrystal versions of the same compound suffer from much poorer overall ZT, thereby thwarting prospects for cost-effective lead-free thermoelectrics. The poor polycrystal bulk performance is attributed to traces of tin oxides covering the surface of SnSe powders, which increases thermal conductivity, reduces electrical conductivity and thereby reduces ZT. Here, we report that hole-doped SnSe polycrystalline samples with reagents carefully purified and tin oxides removed exhibit an ZT of roughly 3.1 at 783 K. Its lattice thermal conductivity is ultralow at roughly 0.07 W m–1 K–1 at 783 K, lower than the single crystals. The path to ultrahigh thermoelectric performance in polycrystalline samples is the proper removal of the deleterious thermally conductive oxides from the surface of SnSe grains. These results could open an era of high-performance practical thermoelectrics from this high-performance material.

Original languageEnglish (US)
Pages (from-to)1378-1384
Number of pages7
JournalNature materials
Volume20
Issue number10
DOIs
StatePublished - Oct 2021

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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