For the first time, we explored the optical, electronic, mechanical, and structural properties of the Ruddlesden–Popper phase family member X₂CaTa₂O₇ (X = Li, Na, K, and Rb) by using density functional theory (DFT) with the Perdew–Burke–Ernzerhof (PBE) function in the generalized gradient approximation (GGA) framework. These materials show promising potential for energy conversion applications. Detailed investigations into structural parameters, band gaps, total and partial densities of states, and optical and mechanical properties demonstrate their suitability for photovoltaic technologies. The calculated electronic band gap structures and density of states demonstrate that X₂CaTa₂O₇ (X = Li, Na, K, and Rb) are semiconductors in nature with band gaps ranging from 1.52 eV to 3.02 eV. Measurements demonstrate substantial contributions from O-2p⁴, Ca-4p⁴, and Ta-4f¹⁴ orbitals to the electronic structures of the compounds. Moreover, the optical characteristics, like the reflectivity, absorption coefficients (10⁵ cm⁻¹), dielectric functions (8.5), refractive index (2–3), and optical conductivity (4–6 fs⁻¹), highlight the abilities of these compounds for optoelectronic and photovoltaic devices. Additionally, the mechanical properties measurements of the compounds show that they are capable for flexible electronic applications as well. This manuscript provides good insights into the design and development of the compounds capable for next-generation photovoltaic devices.

This study presents comprehensive DFT calculations to determine the structural, electronic, mechanical, and optical properties of the Ruddlesden–Popper Phase family member, La₂XO₄, which has an orthorhombic crystal structure with a Cmce space group. Ultrasoft pseudopotential plane wave and PBE-GGA approaches have been implemented using the CASTEP tool. The exchange–correlation approximation calculations show that the La₂XO₄ (where X = Ni, Fe, Ba, and Pb) compounds possess no band gap. The results indicate that the compounds are metallic, which are ideal for supercapacitor (SC) applications. The compound’s optical conductivity, dielectric function, extinction coefficients, absorption refractive index, loss function, and reflectivity are also analyzed for SC applications. UV spectra of the compounds observed high absorption coefficient (10⁵ cm⁻¹), dielectric function (9–10), optical conductivity (7 fs⁻¹), and refractive index (4) values. Furthermore, as B/G > 1.75, the mechanical (elastic) properties have shown ductile behavior and mechanical stability. Using the Born stability criteria, the mechanical stability of the compounds is examined. All of the compounds are ductile, according to Pugh’s and Frantesvich ratios. Finally, time-simulations-dependent temperature stability plots for the compounds are computed by employing dynamical stability with norm-conserved pseudopotential, which confirm their potential for SC applications.