<scp>DFT</scp> Investigations of Non‐Toxic Perovskites <scp>RbZnX₃</scp> (X = F, Cl, and Br): Analyzing the Structural, Electrical, Optical, Mechanical, and Thermodynamic Properties for Suitable Optoelectronic Applications

ABSTRACT Comparative exploration of structural, population analysis, mechanical, electronic, optical, and magnetic properties of a zinc‐based single, non‐toxic, inorganic halide‐based novel perovskite compound RbZnX 3 (X = F, Cl, and Br) without applying pressure by using GGA‐PBE functional within the CASTEP code. Systematic investigations show mechanically stable compound with lattice parameters of the unit cell 4.25, 5.01, 5.50 Å, with indirect bandgaps of 3.637, 1.387, 0.103 eV for RbZnF 3 , RbZnCl 3 , and RbZnBr 3 respectively. Band gap data shows that RbZnX 3 is a semiconductor in nature, and RbZnCl 3 can be an ideal photovoltaic material. From CDD analysis, all three perovskites show a combination of metallic and ionic bonding. Computed optical properties ensure this compound is beneficial in PES and EUV‐based applications, like‐ anti‐reflection surface coating and optoelectronics like solar cells, and it can be a promising element in radiation shielding, spectroscopy, and biotech fields, as well as in high absorption and infrared sectors. High reflectivity makes them suitable as solar cell coating material. Mechanical properties ensure these studied elements' ductility, machinability, and anisotropy. Absorption and reflectivity diminish where energy loss is maximum. For being diamagnetic, it is for superconductors, electromagnetic shielding, and materials testing sectors. Moreover, this study focuses on various applications and possibilities of this compound. Materials are found ductile and RbZnF 3 has an excellent shear and bulk modulus. RbZnF 3 exhibits more significant fracture and plastic deformation resistance than RbZnCl 3 and RbZnBr 3 . Moderate elasticity, flexibility, and strength make these suitable for various applications. The phonon calculation indicates that RbZnF 3 exhibits dynamic stability, whereas instability has been observed in RbZnCl 3 and RbZnBr 3 . An increase in Debye temperature correlates with improved elastic modulus, elevated sound velocity, and higher melting temperature. RbZnBr 3 shows higher heat capacity at ( T &lt; &lt; θ D ) and shows higher energy dispersion or entropy.