Structural and optoelectronic properties of the Cs2InMCl6 (M: Sb, Bi, Ag) double perovskite compounds: A first-principles study

In this work we implied density-functional theory (DFT) to study structural and optoelectronic properties of the double perovskite Cs2InSbCl6 (CISC), Cs2InBiCl6 (CIBC) and Cs2InAgCl6 (CIAC) compounds. We found that structural parameters such as lattice constant and bulk modules are in close agreement with other computational and experimental results. Bandstructure calculations with norm-conserving pseudopotentials show that these compounds are semiconductors with a direct band gap that stay at the Gamma point of the first Brillouin zone. Their band gap values vary from 1.47 to- 3.16 eV. The valence band maximum (VBM) is primarily composed of the Cl-p, In-s, Sb/Bi-s, and Ag-s states, and the conduction band minimum (CBM) is composed of the Cl-s/p, In/ Sb/Bi-p orbitals. Optical studies include dielectric function, absorption, optical conductivity, reflectivity, and refractive and extinction indexes were performed in the photon energy range 0.0 up to 14.0 eV to investigate the optical response of these structures. These compounds have large optical absorption of incident radiation in the range of about 2-14 eV. Therefore, they can potentially be promising candidates for use in optoelectronic devices.