Moiré diamanes based on the hydrogenated or fluorinated twisted bigraphene: The features of atomic and electronic structures, Raman and infrared spectra

We applied density functional theory to predict the atomic and electronic structures, Raman, and IR spectra of the new diamond-like 2D materials – Moiré diamanes (Dns). They are based on the fully hydrogenated or fluorinated twisted bilayer graphenes (tBG) and are formed by interlayer connection. Due to the twisted structure of Moiré bilayer, graphene interlayer connection significantly different from the connection of AA- or AB-stacked bilayer that dictates their property features. We consider characteristics of hydrogenated and fluorinated Moiré diamanes with the simplest unit cell based on the 21.8° tBG- Dn21.8 and F-Dn21.8, respectively. The calculated band structures of considered twisted diamanes show the band gaps higher than 4 eV exceed the gaps of standard diamanes. The presence of a large number of narrow peaks of densities of states (DOS) connected with flattened minizones provides their applicability in optical and optoelectronic devices. To identify Dn21.8 or F-Dn21.8, we calculate and describe Raman and IR spectral features of both structures, which turned out to be similar. The most active Raman frequencies of these Moiré structures are blue-shifted concerning standard AA or AB-stacked diamanes. In contrast to traditionally stacked arrangements, considered twisted diamanes can interact with the light polarized parallel to the film plane.