Energetics and electronic structure of bilayer Janus WSSe

Gao, Yanlin; Okada, Susumu

doi:10.35848/1882-0786/ace33d

Cited by 2 publications

(2 citation statements)

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“…This is beneficial for the stacking of Janus monolayers. For such stacked Janus monolayers, DFT calculation predicts that the dipole moments increase with the number of layers . The aligned dipole moments also split the degenerate energy bands at each layer, forming a staggered band alignment.…”

Section: Resultsmentioning

confidence: 99%

Nanoscrolls of Janus Monolayer Transition Metal Dichalcogenides

Kaneda,

Zhang,

Liu

et al. 2024

ACS Nano

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Tubular structures of transition metal dichalcogenides (TMDCs) have attracted attention in recent years due to their emergent physical properties, such as the giant bulk photovoltaic effect and chirality-dependent superconductivity. To understand and control these properties, it is highly desirable to develop a sophisticated method to fabricate TMDC tubular structures with smaller diameters and a more uniform crystalline orientation. For this purpose, the rolling up of TMDC monolayers into nanoscrolls is an attractive approach to fabricating such a tubular structure. However, the symmetric atomic arrangement of a monolayer TMDC generally makes its tubular structure energetically unstable due to considerable lattice strain in curved monolayers. Here, we report the fabrication of narrow nanoscrolls by using Janus TMDC monolayers, which have an out-of-plane asymmetric structure. Janus WSSe and MoSSe monolayers were prepared by the plasma-assisted surface atom substitution of WSe2 and MoSe2 monolayers, respectively, and then were rolled by solution treatment. The multilayer tubular structures of Janus nanoscrolls were revealed by scanning transmission electron microscopy observations. Atomic resolution elemental analysis confirmed that the Janus monolayers were rolled up with the Se-side surface on the outside. We found that the present nanoscrolls have the smallest diameter of about 5 nm, which is almost the same as the value predicted by the DFT calculation. The difference in work functions between the S- and Se-side surfaces was measured by Kelvin probe force microscopy, which is in good agreement with the theoretical prediction. Strong interlayer interactions and anisotropic optical responses of the Janus nanoscrolls were also revealed by Raman and photoluminescence spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Nanoscrolls of Janus Monolayer Transition Metal Dichalcogenides

Kaneda,

Zhang,

Liu

et al. 2024

ACS Nano

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“…[43][44][45][46][47] Structural asymmetry with respect to the transition metal layer leads to the occurrence of an internal electric field across the layers that causes unique physics in these materials. [48][49][50][51][52] Although Janus TMDs have been synthesized experimentally and their physical properties have been investigated in depth, their formation mechanism remains uncertain in terms of the elemental process of the chalcogen substitutions. Therefore, in this work, we aim to investigate the energetics of Janus WSSe synthesis in terms of the continuous sulfurization and selenization of WSe 2 and WS 2 , respectively, to provide a theoretical insight into the formation mechanisms for Janus TMDs.…”

Section: Introductionmentioning

confidence: 99%

Energetics and electronic structure of Janus WSSe formation by continuous chalcogen substitutions

Gao,

Maruyama,

Okada

2024

Jpn. J. Appl. Phys.

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We investigated the energetics and the electronic structure of Janus WSSe when formed by continuous sulfurization and selenization of WSe$_2$ and WS$_2$, respectively, using density functional theory combined with the effective screening medium method. The total energy of WS$_{2-x}$Se$_x$ is sensitive to the stoichiometry. The total energy increases monotonically as the substitutional surface selenization of WS$_2$ increases. The sulfurization of WSe$_2$ causes complex energetics with respect to the number of S atoms involved. Competition between the energy cost of polarization and the energy gain through S-W bond formation produces the compound WS$_{0.445}$Se$_{1.445}$, which is a metastable structure that gives the local minimum in the energy landscape. The electronic structures of the partially substituted structures are interpolated smoothly from those of Janus WS$_2$ and WSe$_2$. 

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Energetics and electronic structure of bilayer Janus WSSe

Cited by 2 publications

References 50 publications

Nanoscrolls of Janus Monolayer Transition Metal Dichalcogenides

Nanoscrolls of Janus Monolayer Transition Metal Dichalcogenides

Energetics and electronic structure of Janus WSSe formation by continuous chalcogen substitutions

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