Enhancing electronic and optical properties of NiO using Cu-doping: a DFT approach for band gap reduction
Taha Yasin Ahmed, Salah Raza Saeed, Shujahadeen B. Aziz, Omed Gh. Abdullah
Abstract
Abstract The electronic, structural, and optical properties of both pure and Cu-doped NiO have been examined using density functional theory (DFT) with the generalized gradient approximation (GGA) and the Hubbard correction potential (U). Modeling of supercells with Cu concentrations of 6.25% and 12.5% (Ni15CuO16 and Ni7CuO8), the results reveal significant modifications in the optoelectronic characteristics of NiO. The bandgap of pure NiO is 3.07 eV expressively dropped to 1.2 and 1.0 eV for the above mentioned doping levels respectively. The imaginary dielectric function, complex imaginary refractive index, optical conductivity, and energy loss were computed using NiO and Cu-doped NiO absorption coefficient spectra. The DFT approach results demonstrate the capability of Cu insertion on tuning all optical parameters of NiO. The reduction in the sharpness behavior of the NiO absorption spectra, the red shift in the absorption edge, and the observation of an additional absorption feature below the conduction band are evidences for the appearance of acceptor states near the valence band. The noticeable increase in optical absorption in the UV-visible and IR spectra suggests that Cu doped NiO materials suitable for photocatalysis, optoelectronics, and collecting solar energy.