Investigation of optical properties of As2GeSe nanosheet and nanotube based on first-principles calculations

In this paper, the optical properties of nanosheet and (6,6) armchair As2GeSe nanotube (the real and imaginary part of dielectric function, spectrum of energy loss, refractive index, extinction coefficient, and absorption coefficient) are investigated based on the density functional theory. The results obtained from the optical properties of the nanosheet show the anisotropy of this compound, especially at low and middle energies. The behavior of the dielectric function of this material is like a semiconductor material. The main peaks of the imaginary part of dielectric function for in-plane and nanotube growth directions start from low energies up to about 6 eV. The optical transmissions below the Fermi level are associated with the p-orbitals for the As, Ge, and S atoms and above the Fermi level to the p-orbitals of the Se and As atoms. Our results show that the highest reflectance for both in-plane-direction at the energy of 5.66 eV is 46%.