Electronic and optical properties of pristine and alkali metal atom-adsorbed QPHT-graphene: first-principles calculations

In this paper, a pioneering study of the electronic and optical properties of QPHT-graphene after adsorbing three types of alkali metal atoms (Li/Na/K) was conducted using first-principles calculations based on density functional theory. The electronic properties study covers TDOS, PDOS, and Bader charge analyses, in addition to charge density difference. The optical properties study considers the complex dielectric function, complex refractive function, absorption coefficient, reflection coefficient and energy loss function under three types of polarization. The results show that all configurations exhibit a good optical response within a wide energy range of 0–25 eV and are anisotropic under all three polarization types. Under E x and E y polarizations, the adsorption of alkali metal atoms significantly enhances the absorptivity, reflectivity, and refractivity of the pristine QPHT-graphene. As the atomic number increases, it shows a regular oscillatory behavior. Under E z polarization, the QPHT-graphene optical response is concentrated in the high-frequency ultraviolet region, i.e., higher than 10 eV, and alkali metal atom adsorption has little effect on its optical properties. These results show that alkali metal atom adsorption can effectively modulate the optical properties of QPHT-graphene. This research can help to further understand the electronic and optical properties of QPHT-graphene and is instructive in promoting the application of new two-dimensional nanocarbon materials in the field of optoelectronics. Graphic abstract