DFT plus U studies of the electronic and optical properties of ReS2 mono-layer doped with lanthanide atoms

Abstract

The structural, electronic and optical properties of various elements in the lanthanide series as dopant atoms in the triclinic mono-layered rhenium disulphide (ReS2) structure was evaluated using density functional theory with the Hubbard U correction. The Hubbard U correction term was introduced to account for the presence of the electron-electron correlation in the partial filled 4f orbitals of the lanthanide dopant atoms. The calculated lanthanide ion substitutional dopant energies in the ReS2 mono-layer under both the Re-rich and S-rich conditions show that the synthesis of the lanthanide metal doped ReS2 mono-layer is feasible. The pristine ReS2 mono-layer has an electronic band gap of 1.43 eV with a non-magnetic ground state. The introduction of lanthanide atoms (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm) with partial filled 4f orbital modifies the ReS2 mono-layer from non-magnetic to magnetic ground state. The La atom without 4f as well as the Yb and Lu atoms with completely filled 4f orbitals retains its non-magnetic ground state. The presence of the lanthanide dopant atoms in the ReS2 mono-layer modifies the electronic ground structure leading to the introduction of defect states within the energy gap and minute changes in their overall density of states profiles. The calculated optical reflectivity spectra and absorption spectra was modified with significant red-shift observed in the absorption spectra as a result of the dopant atoms. These lanthanide doped ReS2 mono-layer could find potential applications in spintronic and optoelectronic devices