Direct band gap lead-free double perovskite semiconductors Rb2AgB’F6 (B’ = In, Ir) for efficient solar cells: Ab-initio study

In this research, we investigate the structural and optoelectronic properties of Rb 2 AgInF 6 and Rb 2 AgIrF 6 by using Density Functional Theory. The Goldschmidt tolerance factor, phonon dispersion and formation energy demonstrate their thermodynamic stability in the cubic structure. The obtained lattice constants a , by structural optimization, are 9.1070 Å and 8.9155 Å for Rb 2 AgInF 6 and Rb 2 AgIrF 6 compounds, respectively. The examination of the electronic properties shows that the compounds exhibit a direct band gap of 1.81 eV and 1.45 eV for Rb 2 AgInF 6 and Rb 2 AgIrF 6 , respectively, making them promising for photovoltaic applications. In addition, the optical properties analysis, performed over the entire calculated energy spectrum ranging from 0 to 12 eV, shows strong ultraviolet absorption, a high refractive index at low energy, and an improved plasmonic response for Rb 2 AgIrF 6 . These results confirm the potential of the studied materials as high-performance active layers in photovoltaic solar cells. Furthermore, the study of various parameters of CdS/Rb 2 AgIrF 6 /MgCuCrO 2 heterojunction solar cell was investigated using the SCAPS-1D simulator. Under optimized conditions, corresponding to an absorber thickness of 0.6 μ and an acceptor concentration of 10 17 cm −3 , the device achieves a power conversion efficiency (PCE) of η =30.18%, with an open-circuit voltage (Voc) of 1.3661 V, a short-circuit current density (Jsc) of 28.0146 mA/cm 2 , and a fill factor (FF) of 78.85%. These findings demonstrate the promising potential of Rb 2 AgIrF 6 as a lead-free absorber material for next-generation photovoltaic applications.