Electronic structures and optical properties of P and Cl atoms adsorbed/substitutionally doped monolayer MoS2

Using density functional theory calculations, we have studied the electronic and optical properties of doped MoS2, where the Cl and P are incorporated via S substitution or as adsorbates. All the doped structures retain semiconductors, but their band gaps, ranging from 1.56 eV to 1.71 eV, which are smaller than that of the pristine MoS2. This indicates that substitutional doping and adsorption are effective methods to modulate the band gap of MoS2. Moreover, for Cl substitutionally doped and P-Cl co-adsorbed MoS2, the absorption coefficient vertical to c axis can be significantly enhanced in infrared region. In the direction of c axis, the adsorption of P greatly enhance the absorption coefficient of MoS2 in visible region, and P-Cl co-adsorption exhibits additional absorption in infrared and visible region, suggesting their potential application in optoelectronic devices.