Multivalency-Induced Band Gap Opening at MoS<sub>2</sub> Edges

Lucking, Michael; Bang, Junhyeok; Terrones, Humberto; Sun, Yi‐Yang; Zhang, Shou-Cheng

doi:10.1021/acs.chemmater.5b00398

Cited by 52 publications

(104 citation statements)

References 40 publications

(60 reference statements)

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“…The k-resolved density of states of the MoS 2 armchair edge [Eqs. (33) and (34)] is shown in Fig. 6(d).…”

Section: Zigzag and Armchair Edgesmentioning

confidence: 99%

“…As graphene has a relatively simple electronic structure, some features of the edge states in graphene can be studied by analytical or simple numerical techniques [23][24][25]. The edges of MoS 2 have attracted renewed attention recently [14][15][16][17][18][19][20][26][27][28][29][30][31][32][33]. Here, the complexity of the electronic structure requires more extensive models, even for relatively simple modeling at the tight-binding level [34,35], or at the continuum level [36,37].…”

Section: Introductionmentioning

confidence: 99%

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Green's function approach to edge states in transition metal dichalcogenides

2016

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The semiconducting two-dimensional transition metal dichalcogenides MX 2 show an abundance of onedimensional metallic edges and grain boundaries. Standard techniques for calculating edge states typically model nanoribbons, and require the use of supercells. In this paper, we formulate a Green's function technique for calculating edge states of (semi-)infinite two-dimensional systems with a single well-defined edge or grain boundary. We express Green's functions in terms of Bloch matrices, constructed from the solutions of a quadratic eigenvalue equation. The technique can be applied to any localized basis representation of the Hamiltonian. Here, we use it to calculate edge states of MX 2 monolayers by means of tight-binding models. Aside from the basic zigzag and armchair edges, we study edges with a more general orientation, structurally modifed edges, and grain boundaries. A simple three-band model captures an important part of the edge electronic structures. An 11-band model comprising all valence orbitals of the M and X atoms is required to obtain all edge states with energies in the MX 2 band gap. Here, states of odd symmetry with respect to a mirror plane through the layer of M atoms have a dangling-bond character, and tend to pin the Fermi level.

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“…The k-resolved density of states of the MoS 2 armchair edge [Eqs. (33) and (34)] is shown in Fig. 6(d).…”

Section: Zigzag and Armchair Edgesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Green's function approach to edge states in transition metal dichalcogenides

2016

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“…[24][25][26][27]33] Generally, octet electron counting (OEC) rule realized by edge reconstruction, [34,35] surface reconstructions, [36,37] and external atoms passivation [38] has been successfully used in passivating the unpaired electrons in most of the covalent semiconductors. [24][25][26][27]33] Generally, octet electron counting (OEC) rule realized by edge reconstruction, [34,35] surface reconstructions, [36,37] and external atoms passivation [38] has been successfully used in passivating the unpaired electrons in most of the covalent semiconductors.…”

Section: Grain Boundary Passivation Modelmentioning

confidence: 99%

Sodium Passivation of the Grain Boundaries in CuInSe₂ and Cu₂ZnSnS₄ for High‐Efficiency Solar Cells

Chengyan

et al. 2016

Advanced Energy Materials

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It is well known that sodium at grain boundaries (GBs) increases the photovoltaic efficiencies of CuInSe 2 and Cu 2 ZnSnS 4 significantly. However, the mechanism of how sodium influences the GBs is still unknown. Based on the recently proposed self-passivation rule, it is found that the dangling bonds in the GBs can completely be saturated through doping the Na, thus GB states are successfully passivated. It is shown that the Na can easily incorporate into the GB with very low formation energy. Although Cu can also passivate the GB states, it requires a copper rich condition which, however, suppresses the formation of copper vacancies in the bulk and thus decreases the concentration of hole carriers, so copper passivation is practically not as beneficial as sodium. The present work reveals the mechanism about how the Na enhances the photovoltaic performance through passivating the dangling bonds in the GBs of chalcogenide semiconductors, and sheds light on how to passivate dangling bonds in GBs with alterative processes.

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“…Most stable edges are marked with a black box. The edge configurations in panel b are schematic illustrations based on calculated structures …”

Section: Introductionmentioning

confidence: 99%

Stability, Structure and Reconstruction of 1H‐Edges in MoS₂

Sayed‐Ahmad‐Baraza

Ewels

2020

Chemistry A European J

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Density functional studies of the edges of singlelayer 1H-MoS 2 are presented.T his phase presents ar ichv ariability of edges that can influencet he morphology and properties of MoS 2 nano-objects, play an important role in industrial chemical processes, and find future applications in energy storage, electronics and spintronics. The so-called Mo-100 %S edges vertical S-dimersw ere confirmedt ob e stable, however the authors also identified af amilyo fm etastable edges combining Mo atoms linked by two-electron donor symmetrical disulfide ligandsa nd four-electron donor unsymmetrical disulfide ligands. These may be entropically favored, potentially stabilizing them at high temperatures as a" liquid edge" phase. For Mo-50 %S edges, S-bridge structures with 3 periodicity along the edge are the most stable, compatible with aP eierls' distortion arising from the d-bands of the edge Mo atoms.A na dditional explanation for this periodicity is proposed through the formation of 3center bonds.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

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Multivalency-Induced Band Gap Opening at MoS₂ Edges

Cited by 52 publications

References 40 publications

Green's function approach to edge states in transition metal dichalcogenides

Green's function approach to edge states in transition metal dichalcogenides

Sodium Passivation of the Grain Boundaries in CuInSe₂ and Cu₂ZnSnS₄ for High‐Efficiency Solar Cells

Stability, Structure and Reconstruction of 1H‐Edges in MoS₂

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Multivalency-Induced Band Gap Opening at MoS2 Edges

Cited by 52 publications

References 40 publications

Green's function approach to edge states in transition metal dichalcogenides

Green's function approach to edge states in transition metal dichalcogenides

Sodium Passivation of the Grain Boundaries in CuInSe2 and Cu2ZnSnS4 for High‐Efficiency Solar Cells

Stability, Structure and Reconstruction of 1H‐Edges in MoS2

Contact Info

Product

Resources

About

Multivalency-Induced Band Gap Opening at MoS₂ Edges

Sodium Passivation of the Grain Boundaries in CuInSe₂ and Cu₂ZnSnS₄ for High‐Efficiency Solar Cells

Stability, Structure and Reconstruction of 1H‐Edges in MoS₂