Tailoring halide double perovskite materials Rb2MgSnY6 (Y = I, Br, Cl) for enhanced optoelectronic and solar cells through first-principles study

Aiming to enhance halide double perovskites technological applications, this research examines optoelectronic, structural, and mechanical properties of Rb2MgSnY6 (Y = I, Br, Cl) compounds via the first-principles method, evaluating their suitability for prospective applications. The optimised structural parameters and cell volumes expand proportionally with the size of the halogen atoms, and the computed tolerance factors, along with positive phonon frequencies in band structures, confirm both structural and dynamical stability. Electronic band structure analysis reveals that all examined compounds exhibit semiconducting characteristics, with a bandgap of 1.39, 1.95, and 2.45 eV, respectively, for Rb2MgSnI6, Rb2MgSnBr6, and Rb2MgSnCl6. Mechanical analysis confirmed stability criteria and also demonstrated anisotropic and ductile behaviour. A range of optical parameters is analysed, such as dielectric function, absorption rate, optical response, and index of refraction for Rb2MgSnY6 (Y = I, Br, Cl) across the energy range of 0–40 eV. The results of the optical analysis reveal that these materials exhibit high optical conductivity, low reflectivity, and strong absorption ability. Overall, the structural, thermodynamic, and mechanical robustness emphasises the superb prospects of these compounds for deployment in solar cells, photodetectors, light-emitting diodes (LEDs), and various additional optoelectronic appliances.