Exploring the structural, mechanical, electronic, and optical properties of double perovskites of Cs₂AgInX₆ (X = Cl, Br, I) by first-principles calculations

This article presents a comprehensive investigation of the structural, mechanical, electronic, and optical characteristics of double perovskite derivatives Cs₂AgInX₆ (X ​= ​Cl, Br, I) using first-principles calculations. Calculations of elastic constants are used to prove the mechanical stability of the three compounds. Based on the band structures, three Ag-based double perovskites appear to be direct bandgap semiconductors. The bandgap values range from 2.956 ​eV to 0.029 ​eV. We analyze the total and projected densities of states in order to determine the reason behind the bandgap variations. The HSE06 method has been used to explore the optical properties of these compounds in the UV and visible light regions. The optical absorption coefficients are very high for the three double perovskites within the order of 10⁵ ​cm⁻¹. According to our results, the Cs₂AgInBr₆ double perovskite has good physical properties and is suitable for photovoltaic applications.