Study of the Effect of X‐Cation (Br and I) Substitution on the Physical Properties of Novel Inorganic NaCaX ₃ Perovskites

ABSTRACT This study focuses on exploring the exceptional characteristics of NaCaX 3 (X = Br, I), which include the optoelectronic, structural, thermal, and mechanical properties, applying the density functional theory (DFT). The materials have visualized outstanding optoelectronic properties, which make the materials suitable for optoelectronic applications. The investigated band gaps are 3.064 and 2.403 eV for NaCaBr 3 and NaCaI 3 in respectively to which also affected the optical properties, including the dielectric function, reflectivity, optical absorption, conductivity, refractive index, and loss function. In this investigation, the remarkable density of states (DOS) and charge density of the compounds are calculated as well. Encompassing the tolerance factor, formation energy, and octahedral factor, the structural properties are studied to confirm the geometrical stability of the compounds. The low thermal conductivity and high melting temperature of NaCaX 3 (X = Br, I) make them remarkable candidates for high‐temperature applications. Besides, positive Cauchy pressure along with Poisson's and Pugh ratios reveal the ductile nature of the materials observed from the elastic constants, which also ensures the mechanical stability, confirming the Born criterion. Considering these outstanding features, NaCaX 3 (X = Br, I) can be one of the most promising candidates in the future for unlocking a large‐scale application such as solar cell absorber, optoelectronic devices, radiation detectors, etc.