Electronic theory study on the electronic structure and optical properties of S-adsorbed graphene

The effects of coverage and torsional angle on the stability, electronic structure and optical properties of S-absorbed graphene system are studied by using density functional theory based on the first-principles. The adsorption energy, band structure, light absorption coefficient and reflectivity are calculated through it. In the current research area, it is found that the coverage has little effect on the adsorption of the system, but the C atoms are pulled up, the graphene plane is distorted, and the band gap of the graphene is opened, which changes graphene from quasi-metal to semiconductors. S-adsorbed graphene system has a blueshift relative to the intrinsic graphene, and the degree of blueshift increases with the increase of coverage. The reflectivity of the system is higher than that of the unabsorbed S atom system. Torsional deformation has a large effect on its band gap. It makes the adsorption system reduce the adsorption energy and the stability. The band structure shows that the band gap decreases as the twist angle increases. The twisted S-adsorbed graphene system shows a slight redshift, and the degree of redshift increases with the angle. The maximum reflectance of the S-adsorbed graphene system with torsional deformation is stronger than that of the untwisted system.