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 the studied nanomembranes. Observation of relatively weak interlayer interactions suggests that 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, a 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 the 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 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 solar water splitting. The comprehensive vision provided by this study not only confirms the stability and highly attractive electronic and optical characteristics of As₂S₃, As₂Se₃ and As₂Te₃ nanosheets, but also offers new possibilities to design superstretchable nanodevices.