High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band-Extrema Alignment

Xiwen Zhang, Chenhan Liu, Yi Tao, Yunhai Li, Yilv Guo, Yunfei Chen, Xiao Cheng Zeng, Jinlan Wang

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The discovery of a record high figure of merit (ZT) of ≈2.6 associated with bulk SnSe has stimulated considerable enthusiasm in searching for 2D systems with similar high ZT. However, previously reported 2D thermoelectric (TE) materials generally possess very low ZT due to the high lattice thermal conductivity (κL) and/or small power factor (PF). Herein, a very high ZT (≈2.08) value associated with atomically thin 2D KAgSe nanosheet is reported, which also exhibits an unprecedented low intrinsic κL (≈0.03 Wm−1 K−1 at 700 K for trilayer) and fairly large PF. The low κL mainly stems from the high lattice anharmonicity induced by both the “interfacial shear slip” vibrations and the asymmetric “Ag-Se pair” vibrations from distorted AgSe4 tetrahedrons. Meanwhile, the complete band-extrema alignment and coexistence of heavy and light bands result in an optimal Seebeck coefficient and electrical conductivity, thereby a large PF. This work suggests not only an alternative way to acquiring high lattice anharmonicity but also a highly competitive 2D TE candidate for wide applications.

Original languageEnglish (US)
Article number2001200
JournalAdvanced Functional Materials
Volume30
Issue number22
DOIs
StatePublished - May 1 2020

Keywords

  • 2D thermoelectrics
  • band-extrema alignment
  • figure of merit
  • interlayer-related vibration

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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