DFT and SCAPS-1D investigation of Ae 2 LiSbI 6 (Ae = Rb, Cs) perovskites for solar energy applications

molecular dynamics (AIMD) and phonon dispersion analysis. Their indirect band gaps, 1.694 eV for Rb2LiSbI6 and 1.733 eV for Cs2LiSbI6 (GGA-PBE), and 1.721 eV and 1.763 eV for Rb and Cs, respectively (HSE06), fall within the optimal range for visible-light absorption, while their strong optical responses, characterized by high absorption coefficients and low reflectivity, underscore their excellent potential for efficient solar photon harvesting. SCAPS-1D simulations further predict power conversion efficiencies (PCEs) approaching 28%, positioning these double perovskites as promising and competitive candidates for next-generation photovoltaic technologies, based on theoretical screening and idealized device simulations. These findings not only expand the family of environmentally benign perovskites but also provide insights into the design of stable, high-performance absorbers for sustainable solar cells.