Interlayer Coupling Induced Phonon-Glass-Electron-Crystal Behavior in van der Waals Heterostructure PtSe2/γ-GeSe

Muhammad Sajjad, Nirpendra Singh

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We report the electronic band structure and interlayer coupling induced phonon-glass-electron-crystal behavior in the van der Waals heterostructure PtSe2/γ-GeSe. The heterostructure is dynamically stable and possesses an indirect band gap of 0.63 eV (at the Heyd-Scuseria-Ernzerhof functional level) with type II band alignment. A low conduction band offset of 0.20 eV compared to the valence band offset of 0.92 eV suggests fluent electrons drive from γ-GeSe to PtSe2. Interlayer coupling induced strong phonon coupling and a unique "avoided crossing" feature between longitudinal acoustic and low-lying optical phonon modes between K and Γ points. Significant suppression of acoustic phonon modes and giant phonon scattering rates (a maximum value of 73.76 ps-1) results in a low lattice thermal conductivity of 1.20 W/(m·K) at 300 K after enforcing the mandatory rotational invariance condition. The calculated lattice thermal conductivity is 14-fold smaller than that of monolayer PtSe2(16.97 W/(m·K)). The lattice thermal conductivity upsurges by 24% as the out-of-plane acoustic phonon dispersion undergoes linear dispersion, indicating the importance of pure quadratic flexural phonon dispersion. Our results disclose a strategy for having the phonon-glass-electron-crystal character in van der Waals heterostructures.

Original languageBritish English
Pages (from-to)13610-13616
Number of pages7
JournalACS Applied Energy Materials
Volume5
Issue number11
DOIs
StatePublished - 28 Nov 2022

Keywords

  • double-layer honeycomb lattice
  • first-principles calculations
  • lattice thermal conductivity
  • phonon avoided crossing
  • phonon-glass-electron-crystal

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