Theoretical study of the Sb-substitution effect on the optoelectronic properties of Cs2AgBiBr6 double perovskite

Abstract

Cubic structures of the 2 × 2 × 1 supercells of Cs 2 AgBiBr 6. • Analysis of the structure of the double perovskite Cs 2 AgBiBr 6 with density functional theory (DFT) using various doping levels of Sb (x = 0.0625, 0.125, 0.1875). • This study investigates the electronic structure of both pure and Sb-doped Cs 2 AgBiBr 6 configurations, focusing particularly on the total density of states (TDOS) and atomic orbital densities. • The undoped structure of Cs 2 AgBiBr 6 exhibits a maximum absorption coefficient of 7.65 × 10 4 cm −1 at a wavelength of 285 nm. • Optical properties, including reflectivity, absorption coefficient, refractive index, dielectric function, optical conductivity, and loss function, were analyzed. • Doping Cs 2 AgBiBr 6 with Sb reduces the band gap energy and enhances absorption in the visible spectrum, suggesting that Sb-doped Cs 2 AgBiBr 6 is promising for photovoltaic applications. We analyzed the structure of the double perovskite Cs 2 AgBiBr 6 utilizing Density Functional Theory (DFT), adding different doping concentrations of the Sb atom (Cs 2 AgBi 1-x Sb x Br 6 , with x = 0.0625, 0.125, 0.1875). The investigation concentrated on the electronic structure of both pure and doped configurations, emphasizing the total density of states (TDOS) and the atomic orbital densities for each structure. The pure structure exhibits a maximum absorption coefficient of 7.65 × 10 4 cm −1 at a wavelength of 285 nm. Furthermore, we assessed multiple optical properties including reflectivity (R), absorption coefficient (α), refractive index (n*), dielectric function (ε), optical conductivity (σ), and loss function L(ω). The findings demonstrate that Sb doping diminishes the bandgap energy and increases the absorption coefficient in the visible spectrum. The enhancements indicate that Sb-doped Cs 2 AgBiBr 6 hold significant potential for photovoltaic (PV) applications.