Study of the structural, electronic, optical, and elastic properties of NaSrX3 (X = Br and I) perovskites using Density Functional Theory (DFT) with GGA formalism

The electronic and optical properties of NaSrX3 (X = Br, I) perovskites using density functional theory (DFT) with GGA (Generalized Gradient Approximation) formalism. The lattice parameters obtained are 5.22 Å and 5.74 Å for NaSrBr3 and NaSrI3, respectively. NaSrBr3 and NaSrI3 have direct gaps of 2.51 eV and 1.49 eV, respectively. They all have a conduction band dominated by 3d statesof Sr, weakly mixed with 3s states of Na and 4s states of Sr. The valence band is dominated by the 2p states of the alkali metal and the 3d states of Sr. These perovskites also have very good optical properties: low reflectivity and high absorption in the ultraviolet. Observation of the different optical functions shows that the materials can slow down and deflect light in both the visible and ultraviolet ranges. Light can also be absorbed in energy ranges corresponding to the visible and UV spectrums. They are also transparent between 10 eV and 20 eV. These materials are suitable for various applications in both the visible and UV spectrums. The elastic properties of NaSrBr3 and NaSrI3 are also very interesting. The elastic constants found verify the criteria for mechanical stability. NaSrBr3 and NaSrI3 are ductile and likely to be ionic. They are anisotropic and stable materials. NaSrBr3 has a higher melting point than NaSrI3. This work confirms that NaSrBr3 and NaSrI3 have very good electronic, optoelectronic, elastic, and optical properties. Their use in a photovoltaic cell could increase its conversion efficiency.