Abstract
Similar to graphene, the subject of stanene has stolen significant recognition both in experimental and theoretical areas. Nevertheless, stanene is poor when put into practice because it has zero band-gap energy, therefore it is necessary to use a universal strategy to achieve a material with a large band-gap. Employing density functional theory, we study the structural, electronic, and optical properties such as dielectric function and absorption coefficient of stanene monolayer functionalized with chemical groups, i.e., W-Sn-Z, Cl-Sn-Br, and W'-Sn-W' (where W = Cl, F, or OH; Z = CN; and W' = CN, CH, or NH). Our calculations reveal that the band-gap energy at the high symmetry points tuned in a range of 1.019-1.751 eV, which is significantly higher than the stanene monolayer with hydrogenation (0.3 eV). Furthermore, we found that under an external electric field the electronic band structures of various compounds are changed down in energy producing in a semiconductor to metal transition. Furthermore, we have computed other properties like the absorption coefficient, the refractive index, and the conductivity of our systems.