Abstract
Despite of getting higher efficiencies from hybrid perovskite solar cells, it is necessary to investigate stable and desirable bandgap materials. We introduced new promising class of double perovskites (DPs) materials using density functional theory predictions, for solar cells applications. The results of band structure show that Er along with the co-doped Fe and Yb of NaBiF6 with intermetallic nature. The optical properties have studied by considering interband transitions, where many levels of optical transitions is observed. We calculated optical dispersions e.g real and imaginary parts of complex dielectric function, energy loss function, reflectivity, absorption coefficient, refractive index and optical conductivity as function of photon energy from 0 to 14 eV for both spins up and down polarizations. The investigated materials contains high spin symmetry except at low energies, weakly photons reflected in IR and visible regions and absorb photons strongly in the UV region. These optical properties may be used for applications in optoelectronic devices.