DFT Study of Electronic and Optical Properties of Cu2O Nanostructures

The DFT calculations are performed with LDA, GGA and mGGA functionals without spin orbit interactions for cuprous oxide cluster structures of various sizes. The band structure, density of states and optical spectra are calculated for different sizes of Cu2O cluster structures ranging from 0.5 nm to 3 nm. The calculated values of band gap for Cu2O show large variations with different functionals. The band gap calculated for the structures of lowest size shows a rapid increase with cluster size and follows a plateau for the sizes larger than 1.5 nm. This band gap sensitivity with cluster size can be utilized for customizing the band gap of the material by adjusting the particle size. The shift of refractive index minima towards shorter wavelengths is also observed from the optical spectra. Not much experimental and theoretical data in this size range are available for comparison. The results of calculations are compared with the scant data wherever available.