Interlayer interaction mechanism and its regulation on optical properties of bilayer SiCNSs

Silicon carbide nanosheets (SiCNSs) have a very broad application prospect in the field of new two-dimensional (2D) materials. In this paper, the interlayer interaction mechanism of bilayer SiCNSs (BL-SiCNSs) and its effect on optical properties are studied by first principles. Taking the charge and dipole moment of the layers as parameters, an interlayer coupling model is constructed which is more convenient to control the photoelectric properties. The results show that the stronger the interlayer coupling, the smaller the band gap of BL-SiCNSs. The interlayer coupling also changes the number of absorption peaks and causes the red or blue shift of absorption peaks. The strong interlayer coupling can produce obvious dispersion and regulate the optical transmission properties. The larger the interlayer distance, the smaller the permittivity in the vertical direction. However, the permittivity of the parallel direction is negative in the range of 150-300 nm, showing obvious metallicity. It is expected that the results will provide a meaningful theoretical basis for further study of SiCNSs optoelectronic devices.