Sliding Modulation in Nonlinear Optical Effect in Two-Dimensional van der Waals Cu₂MoS₄

Abstract

Owing to different nonlinear optical (NLO) motifs with diverse structural and symmetrical assemblies, two-dimensional (2D) van der Waals (vdW) transition metal ternary chalcogenides (TMTCs) have unique advantages in nano-NLO modulation compared to 2D vdW transition metal dichalcogenides (e.g., MoS2). Based on first-principles calculations, in this study, we discover that layered Cu2MoS4 with two tetrahedral [MoS4] and [CuS4] motifs, as a representative 2D vdW TMTC, has an extremely rare sliding-modulated second harmonic effect with nearly 70% fluctuation, much larger than 5% in MoS2 with a single octahedral [MoS6] motif because of different synergistic effects among intra- and interlayer NLO polarizations induced by the [CuS4] and [MoS4] NLO-active motifs. Furthermore, the Cu2MoS4 layers exhibit a low energy barrier in interlayer sliding with a robust SHG response against large strains, displaying a novel and applicable NLO-modulation mechanism in nano-optoelectronics.

Second Harmonic Generation Control in 2D Layered Materials: Status and Outlook

“…Other materials, such as ternary layered compounds, e.g. SnP 2 S 6 , [ 142 ] Nb 3 SeI 7 , [ 199 ] NbOI 2 , [ 84 ] Cu 2 MoS 4 , [ 200 ] and quaternary layered chalcogenides, e.g. CuInP 2 S 6 , [ 83,141 ] AgInP 2 S 6 , [ 201 ] have exhibited strong SHG response due to their intrinsic noncentrosymmetric structures.…”

Preparation and photocatalytic hydrogen evolution performance of square platform Cu2MoS4/lamellar ZnIn2S4

“…[1][2][3][4][5] Cu 2 MoS 4 belongs to transition metal sulfides with a twodimensional layered stacking structure and differs from other layered materials with hexagonal structure, showing a special tetragonal structure. [6][7][8] Lin and Gan et al 9,10 demonstrated that Cu 2 MoS 4 has electrons confined to Mo atoms and holes confined to Cu and S atoms, and Cu atoms, contributing off-domain s-electrons, have little effect on the band gap width. Due to its unique physicochemical properties, suitable band gap structure and elemental abundance, this material has great potential advantages in the field of photocatalysis.…”

Thermal conductivity of sliding bilayer h-BN and its manipulation with strain and layer confinement

“…For bilayer structures, van der Waals sliding will change the lattice pattern and break the symmetry, thereby modulating the electrical, optical and magnetic properties of 2D materials. [5][6][7] Experimentally, Yasuda et al demonstrated an out-of-plane ferroelectric polarization in staggered bilayer h-BN, 8 which is switchable by sliding one layer with respect to the other layer. The switching of electrical polarization is usually driven by the external forces, for example an external electric field.…”