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 Rb2AgInF6 and Rb2AgIrF6 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 Rb2AgInF6 and Rb2AgIrF6 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 Rb2AgInF6 and Rb2AgIrF6, 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 Rb2AgIrF6. 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/Rb2AgIrF6/MgCuCrO2 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 1017 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/cm2, and a fill factor (FF) of 78.85%. These findings demonstrate the promising potential of Rb2AgIrF6 as a lead-free absorber material for next-generation photovoltaic applications.