A Comprehensive Study of Electronic, Optical, and Thermoelectric Characteristics of Cs(2)PbI(2)Br(2) Inorganic Layered Ruddlesden–Popper Mixed Halide Perovskite through Systematic First-Principles Analysis

[Image: see text] In this research, we present a comprehensive study on the influence of layer-dependent structural, electronic, and optical properties in the two-dimensional (2D) Ruddlesden–Popper (RP) perovskite Cs(2)PbI(2)Br(2). Employing first-principles computations within the density functional theory method, including spin orbit coupling contribution, we examine the impact of various factors on the material. Our results demonstrate that the predicted 2D-layered RP perovskite Cs(2)PbI(2)Br(2) structures exhibit remarkable stability both structurally and energetically, making them promising candidates for experimental realization. Furthermore, we observe that the electronic band gap and optical absorption coefficients of Cs(2)PbI(2)Br(2) strongly depend on the thickness variation of the layers. Interestingly, Cs(2)PbI(2)Br(2) exhibits a notable absorption coefficient in the visible region. Using a combination of density functional theory and Boltzmann transport theory, the thermoelectric properties were forecasted. The calculation involved determining the Seebeck coefficient (S) and other associated thermoelectric characteristics, such as electronic and thermal conductivities, as they vary with the chemical potential at room temperature. These findings open up exciting opportunities for the application of this 2D RP perovskite in solar cells and thermoelectric devices, owing to its unique properties.