Electronic structure and optical properties of two-dimensional M2CF2 (M=Y, Lu) MXenes

As a new family of 2D materials, transition metal carbides and nitrides (MXenes) have attracted growing attention in recent years due to their widespread potential applications. In this study, the electronic structures and optical properties of MXenes M2CF2 (M=Y, Lu) have been investigated using density functional theory (DFT) calculations. Based on the results, the Y2CF2 (Lu2CF2) monolayer is a semiconductor with indirect bandgap of 1.67 eV (1.42eV). Comparing the electronic bandgap of Y2CF2 and Y2CCl2 demonstrates the dependency of electronic and optical properties of these materials to the surface termination taking place during the experimental preparation of MXenes. To study the optical properties, the real and imaginary parts of the dielectric function was calculated. According to the results, there is a remarkable absorption in the ultraviolet and visible regions that they have better absorption compared to that of BP, MoS2 and Sc2CO2 monolayer compositions in the visible region. We have also considered electron energy loss function, refractive index and optical conductivity of the structures. All obtained results express that M2CF2 (M=Y, Lu) monolayers are good candidates for electronic, optoelectronic and solar energy applications.