Propriétés électroniques et optiques des pérovskites inorganiques halogénées de type ASiI3 (A=Li, Na, K, Rb et Cs) par la méthode de la Théorie de la Fonctionnelle de la Densité (DFT)

Abstract

Electronic and optical properties of halogenated inorganic perovskites of the type ASiI3 (A = Li, Na, K, Rb, and Cs) using Density Functional Theory (DFT)

The electronic and optical properties of halogenated perovskites of the ASiI₃ type (with A = Li, Na, K, Rb and Cs) were studied. This was done by the Theory of Functional Density (DFT) method using Quantum Expresso software. We used the Generalized Gradient Approximation (GGA). The results show that the electronic (gaps and densities of states) and optical (dielectric functions) properties are slightly affected by alkali A. The energies of the gaps obtained are between 1.20 eV and 1.60 eV. The mesh parameters, determined by relaxation, are between 4.20 Å and 5.56 Å. After analysis, we note that for each structure, the conduction band is composed of 5p-I and 3p-Si state with a significant part of 3s-Si state. These states (5p-I and 3p-Si) are weakly mixed with the 3s-Si state and the p state of the last sublayer of the corresponding alkali except in LiSiI3. This work on electronic and optical properties proves that these ASiI₃-type perovskites are indeed semiconductor materials that can be used in optoelectronic devices. They can therefore serve as active layers in solar cells for an appreciable and promising yield.

 Keywords: Perovskites; Density Functional Theory; Electronic properties; Optical properties.