Pd2Se3 Monolayer: A Promising Two-Dimensional Thermoelectric Material with Ultralow Lattice Thermal Conductivity and High Power Factor

S. Shahab Naghavi*, Jiangang He, Yi Xia, Chris Wolverton

*Corresponding author for this work

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

A high power factor and low lattice thermal conductivity are two essential ingredients of highly efficient thermoelectric materials. Although monolayers of transition-metal dichalcogenides possess high power factors, high lattice thermal conductivities significantly impede their practical applications. Our first-principles calculations show that these two ingredients are well fulfilled in the recently synthesized Pd2Se3 monolayer, whose crystal structure is composed of [Se2]2- dimers, Se2- anions, and Pd2+ cations coordinated in a square-planar manner. Our detailed analysis of third-order interatomic force constants reveals that the anharmonicity and soft phonon modes associated with covalently bonded [Se2]2- dimers lead to ultralow lattice thermal conductivities in Pd2Se3 monolayers (1.5 and 2.9 W m-1 K-1 along the a- and b-axes at 300 K, respectively), which are comparable to those of high-performance bulk thermoelectric materials such as PbTe. Moreover, the "pudding-mold" type band structure, caused by Pd2+ (d8) cations coordinated in a square-planar crystal field, leads to high power factors in Pd2Se3 monolayers. Consequently, both electron- and hole-doped thermoelectric materials with a considerably high zT can be achieved at moderate carrier concentrations, suggesting that Pd2Se3 is a promising two-dimensional thermoelectric material. Our results suggest that hierarchical chemical bonds, that is, coexistence of different types of chemical bonds, combined with a square-planar crystal field is a promising route for designing high-efficiency thermoelectric materials.

Original languageEnglish (US)
Pages (from-to)5639-5647
Number of pages9
JournalChemistry of Materials
Volume30
Issue number16
DOIs
StatePublished - Aug 28 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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