Comprehensive first-principles study of structural, electronic, optical, and elastic properties of FrBCl3 (B = Mg & Ba) cubic perovskites

Lead free metal halide Perovskites have recently received attention for their use in light-emitting diodes, solar cells, lasers and other optoelectronic devices. To investigate the structural, electronic, optical and mechanical characteristics of the non-toxic metal halides FrBCl₃ (B = Mg, Ba), the first principles calculation has been performed implementing full-potential linearized augmented plane wave approach (FP-LAPW) in the density functional theory (DFT) in WIEN2k code. As Mg atom is replaced by Ba atom, the lattice parameter has also increased which also affected in other optoelectronic properties. The simulated band structures and density of states reveal that both of these compounds have indirect wide bandgap, which are 3.77 eV for FrMgCl₃ and 4.52 eV for FrBaCl₃. The optical spectra demonstrate that absorbance enhanced about $2.2\times {10}^6{\mathrm{cm}}^{-1}$ in the ultraviolet region (16–17 eV). The highest peak values of conductivity, dielectric constant and low reflectivity have also been observed in the ultraviolet region. The investigation of mechanical properties reveal that the composites are mechanically stable. According to a comprehensive study of the physical characteristics, FrBaCl₃ may be a possibility for optoelectronic uses. As FrBaCl₃ contains the radioactive element, this may be used in medical sector for diagnosis and imaging technology.