DFT and TD‐DFT Study of Al‐Based Fluoro‐Perovskites AlMF 3 (M = Ca, Zn, Ge) for Photovoltaic Applications

ABSTRACT Perovskite materials have emerged as a focal point for scientific research, owing to their ability for plausible applications in optoelectronic and photovoltaic systems. We have explored Al‐based fluoro‐perovskite compounds AlMF 3 (M = Ca, Zn, Ge) studied through Density Functional theory (DFT) and Time‐Dependent (TD)‐DFT methodology. Functional CAM‐B3LYP/ LanL2MB and CAM‐B3LYP/LANL2DZ are employed for geometry optimization. This study examined the structural, optoelectronic, and thermochemical properties of these materials. The tolerance factors of AlCaF 3 , AlZnF 3, and AlGeF 3 are found as 0.85, 0.93, and 0.96. The negative formation energy of AlMF 3 compounds indicates thermodynamic stability. The HOMO–LUMO gap of AlCaF 3 , AlZnF 3 , and AlGeF 3 using LANL2MB is obtained as 2.82, 2.44, and 2.40 eV, respectively, whereas using LANL2DZ it is found in the range of 1.90–2.40 eV. AlGeF 3 and AlCaF 3 exhibit a minimum and maximum energy gap, respectively. CDFT‐based descriptors of AlMF 3 are analyzed and discussed. Among the examined fluoro‐perovskites, AlCaF 3 exhibits high stability. AlGeF 3 shows the maximum value of electronegativity, which indicates that it has high electron‐accepting capability. The refractive index and dielectric constant of these fluoro‐perovskite increase as the replacement of the M‐site cation, Ca to Zn to Ge, takes place. The thermochemical properties of these materials are also calculated. The estimated findings show a pattern consistent with earlier reports on perovskite materials.