Crystal structure 1 DFT 1 Density functional theory 1 Density-functional-theory 1 Dielectric devices 1 Dielectric interference filters Dielectric resonator filters 1 Double Perovskites 1 Double perovskites 1 Electronic properties 1 Energy gap 1 Excitons 1 Lower energies 1 MBJ 1 Optical correlation 1 Optical properties 1 Optical response 1 Perovskite 1 SXRD 1 UV/ Vis spectroscopy 1 UV–Vis spectroscopy 1 mBJ 1