Prediction of a rippled and auxetic two-dimensional Sn9C15 layers with tunable electronic band structure: A first-principle study

We predicted a two-dimensional Sn9C15 monolayer with regular ripple using first-principles methods by utilizing the VASP code based on density functional theory (DFT). The rippled Sn9C15 monolayer is an indirect bandgap semiconductor with anisotropic mechanical properties (Poisson’s ratio and Young’s modulus). It exhibits auxetic properties with a negative Poisson’s ratio (NPR) of up to −0.58 and exceptional flexibility in the x direction. Furthermore, its bandgap can be adjusted from 1.16 eV to 0.68 eV with a strain in the x direction of less than 12 %. The rippled Sn9C15 monolayer is sensitive to polarized light and has a broad absorption spectrum from infrared to ultraviolet. In addition, the bilayer rippled Sn9C15 exhibits a regularly arranged nanotube-like structure and is a stable direct bandgap semiconductor material. These findings enrich the emerging landscape of 2D rippled monolayers and suggest potential applications in diverse fields such as optics, nanomechanics, electronic devices, and filtration. [Display omitted]