Tuning electronic structure and optical properties of ZnO monolayer by Cd doping

Structural, electronic and optical properties of Cd-doped ZnO monolayer have been investigated using first-principles density-functional theory based on the local density approximation plus Hubbard U approach, which precisely predicts the band gap. The formation energy of doped system is negative, implying a stable incorporation of Cd. The band gaps of Cd-doped ZnO monolayer decrease with increasing Cd concentration. Furthermore, Cd doping is found to result in a red-shift of the absorption peaks, enhancing the visible light absorption. These findings demonstrate that Cd-doped ZnO monolayer could display potential application in optoelectronic and photocatalytic fields.