As₂S₃, As₂Se₃ and As₂Te₃ nanosheets: superstretchable semiconductors with anisotropic carrier mobilities and optical properties

Abstract

In this work, density functional theory calculations were carried out to explore the mechanical response, dynamical/thermal stability, electronic/optical properties and photocatalytic features of monoclinic As2X3 (X=S, Se and Te) nanosheets. Acquired phonon dispersions and ab-initio molecular dynamics results confirm the stability of studied nanomembranes. Observation of relatively weak interlayer interactions suggests that the exfoliation techniques can be potentially employed to fabricate nanomembranes from their bulk counterparts. The studied nanosheets were found to show highly anisotropic mechanical properties. Notably, new As2Te3 2D lattice predicted by this study is found to exhibit unique superstretchability, which outperforms other 2D materials. In addition, our results on the basis of HSE06 functional reveal the indirect semiconducting electronic nature for the monolayer to few-layer and bulk structures of As2X3, in which a moderate decreasing trend in the band-gap by increasing the thickness can be established. The studied nanomaterials were found to show remarkably high and anisotropic carrier mobilities. Moreover, optical results show that these nanosheets can absorb the visible light. In particular, the valence and conduction band edge positions, high carrier mobilities and optical responses of As2Se3 nanosheets were found to be highly desirable for the solar water splitting. The comprehensive vision provided by this study not only confirm the stability and highly attractive electronic and optical characteristics of As2S3, As2Se3 and As2Te3 nanosheets, but also offer new possibilities to design superstretchable nanodevices.

The external electric‐field‐induced Schottky‐to‐ohmic contact transition in graphene/ As 2 S 3 interface: A study by the first principles

“…The photon energy was shifted with a scissor operator based on the bandgap difference between PBE and HSE results. After shifting, we found our results for As 2 S 3 are similar to that in Reference 21, implying the reliability of our results. It seems that the external electric field ( E ext ) almost not affect the optical absorption of As 2 S 3 in the whole photon energy range, and graphene as well as the graphene/As 2 S 3 interface in the visible and ultraviolet regions.…”

“…Before contacting, the lattice constants of graphene are a 1 = b 1 = 2.46 Å, and of As 2 S 3 are a 2 = 4.41 Å = 11.42 Å, respectively, which agrees well with that in References 12 and 21. Subsequently, we used our python code heterojunction to build heterostructures automatically.…”

“…To evaluate the dynamical stability of a certain material, the phonon spectra are a necessity 20 . Theoretically, 2D As 2 S 3 was proved with promising photocatalytic ability by Mortazavi et al, as well as the dynamical and thermal stabilities by doing phonon spectra and ab initio molecular dynamics (AIMD) simulations 21 . In our unpublished work, we have predicted the high mechanical and electronic anisotropy of 2D As 2 S 3 , and the imaginary frequency‐free phonon spectra under 6% tensile strain condition further proved the valuable application of 2D As 2 S 3 in the future.…”

Naturally occurring van der Waals materials

“…Recently, Manjón and colleagues 79 studied the vibrations, structure, and electronic properties of orpiment under high pressure, finding that pressure is able to tune its metavalent bonding thus turning orpiment from a semiconductor into an "incipient metal" with promising phase-change, thermoelectric and topological insulating properties. Mortazavi et al 80 have calculated the mechanical properties and the mobility of orpiment nanosheets reporting a strong anisotropy in the mechanical properties: along one crystal direction orpiment is elastic and brittle, whereas along the perpendicular direction it shows superstretchability, similar to rubber. Interestingly, Steeneken and colleagues 81 isolated a single layer and few layers of orpiment by mechanical exfoliation and tested their strong vibrational and mechanical anisotropy, arising from its crystal structure, finding a Young's modulus of E a-axis = 79.1 ± 10.1 GPa and E c-axis = 47.2 ± 7.9 GPa along the two main crystalline directions 81 .…”

Two-dimensional silicon bismotide (SiBi) monolayer with a honeycomb-like lattice: first-principles study of tuning the electronic properties

“…Modulating the band gap of 2DMs can be obtained by various external means: applications of different types of vertical and in-plane strains, application of an electric eld, doping, surface/edge functionalization, varying thickness of the 2DM, and heterostructure formation, are a few examples. [40][41][42][43][44] In this work, using density functional theory, we proposed a novel 2D silicon bismotide (SiBi) with a layered GaSe-like crystal structure that possesses a low indirect band gap of 0.65 eV, calculated using HSE06 with inclusion of the spin orbit coupling effect. Ab initio molecular dynamic simulations at 300 K and phonon dispersion calculations suggest its good thermal and dynamical stability.…”