Study of structural, electronic, optical and mechanical properties of K2ScCuF6 and K2YCuF6 perovskites via DFT calculations

Owing to their outstanding performance, environmental friendliness and stability, perovskite materials are becoming very important for solar cells, renewable energy sources and thermoelectric generators. This work uses the first-principles approach to explore the structural, electronic, optical and elastic characteristics of K2ScCuF6 and K2YCuF6 double perovskites. The negative formation energy in Birch-Murnaghan confirms the stability of the compounds in Fm3m (2 2 5) space group. The analysis of the electronic properties concluded that both K2ScCuF6 and K2YCuF6 are narrow band gap semiconductors materials, having 1.2 and 2.3 eV of bandgap energies, respectively. This was further verified by the density of states. The mechanical stability, ductility and anisotropic nature of the compounds was shown by analyzing their elastic constants. In addition, the optical properties showed transparency at low energy values but showed both transmission and absorption characteristics at higher energy levels. These interesting results imply that K2ScCuF6 and K2YCuF6 have significant potential in solar cells, light-emitting diodes (LEDs), smart windows, displays and sensors.