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Issue 47, 2019
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Ultra-low lattice thermal conductivity of monolayer penta-silicene and penta-germanene

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Abstract

We study the lattice thermal conductivity of two-dimensional (2D) pentagonal systems, such as penta-silicene and penta-germanene. Penta-silicene has been recently reported, while the stable penta-germanene, made up of another group IV element, is first revealed by our ab initio calculations. We find that both penta-silicene and penta-germanene at room temperature have ultra-low lattice thermal conductivities, κ, of 1.29 W m−1 K−1 and 0.30 W m−1 K−1, respectively. To the best of our knowledge, penta-germanene may have the lowest κ in 2D crystal materials. We attribute the ultra-low κ to the weak phonon harmonic interaction and strong anharmonic scattering. A small phonon group velocity, a small Debye frequency, a large Grüneisen parameter, and a large number of modes available for phonon–phonon interplay together lead to the ultra-low κ of penta-silicene and penta-germanene. These discoveries provide new insight into the manipulation of ultra-low κ in 2D materials and highlight the potential applications of silicon and germanium based high thermoelectric materials.

Graphical abstract: Ultra-low lattice thermal conductivity of monolayer penta-silicene and penta-germanene

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Publication details

The article was received on 24 Sep 2019, accepted on 30 Oct 2019 and first published on 30 Oct 2019


Article type: Paper
DOI: 10.1039/C9CP05246A
Phys. Chem. Chem. Phys., 2019,21, 26033-26040

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    Ultra-low lattice thermal conductivity of monolayer penta-silicene and penta-germanene

    Z. Gao, Z. Zhang, G. Liu and J. Wang, Phys. Chem. Chem. Phys., 2019, 21, 26033
    DOI: 10.1039/C9CP05246A

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