Effects of transition metal (Fe, Co & Ni) doping on structural, electronic and optical properties of CuO: DFT + U study

Abstract

To investigate the structural, electronic and optical properties of CuO and transition metal (Ni, Fe & Co) doped CuO, first-principles calculation is performed based on standard DFT and DFT + U. The use of DFT + U calculations confirm that the growth of the CuO films is p-type in nature with an indirect bandgap of 1.58 eV which is in good agreement with the experimental results. When doped with transition metals, the band gap value decreased to be 1.51 eV with iron (Fe). While the band gap increased to be 1.6 eV with Co doping, by directly contributing in valence band maxima (VBM) formation. Shallow impurity states also formed on top of valance band when doped with Fe and Co and which in turn can reduce recombination rate acting as carrier traps leading to better quantum efficiency. Net effective magnetic moment for Co, Ni and Fe doping was measured to be 1.958 μ B , 0.972 μ B and 0.997 μ B respectively originating from spin splitting of valance and conduction bands which may improve the photocatalytic efficiency and raise the recycle rate of photocatalysts. Calculated real and imaginary part of dielectric constant also matched with experimental literatures. Significant absorptivity of CuO with low reflectivity and maximum refractive index in visible range along with excellent tunability through doping was also observed. Thus, it can be concluded that, these changes in band structure and optical properties accompanied by generation of net magnetic moment due to doping open up wide window for novel strategies of tailoring properties for desired applications.