First-principles study of structural, electronic and optical properties of doped Ti2CF2 MXenes

Abstract

The structural, electronic and optical properties of the doped Ti2CF2 MXenes by Si, Ge, Sn, F, B, N, and S atoms are investigated by density functional theory. The analysis of cohesive energy and the binding energy indicates that the doped Ti2CF2 MXene by N atom has the stablest structure, while the doped Ti2CF2 MXene by Si, Ge, and Sn atoms are not so favorable. The doped atom has little effect on the electronic properties, and all studied doped Ti2CF2 MXene monolayers exhibit metallic character. If the C vacancy of the pure Ti2CF2 MXene is filled with Si, Sn, or Ge atom, additional bands appear around the Fermi energy, and the p-level of the doped atoms shifts towards the Fermi energy with the increasing diameter of doped atoms. Most of the studied Ti2CF2 MXenes are promising dielectric materials, and the studied MXenes have the maximum absorption coefficient at about 34.3 nm in the infrared region. Absorption coefficients of the pure Ti2CF2 and Ti2CF2 with B atom almost decrease to zero with the increasing wavelength, while other doped Ti2CF2 single layers have larger absorption coefficients.