Quantum-Engineered LiXO₂ (X = Co, Ni) Delafossites: First-Principles Design of Structural, Optoelectronic, Thermodynamic, and Magnetic Frameworks for Next-Generation Energy Harvesting

Abstract

The structural, optoelectronic, and magnetic properties of LiXO₂ (X = Co, Ni) delafossite compounds are evaluated using first-principles based DFT calculations to investigate their potential applications in optoelectronic and spintronic devices. Based on calculated ground state energies, LiNiO₂ is a more stable compound, compared to LiCoO₂. The indirect energy band gap for LiCoO₂ and LiNiO₂ are 4.95 and 5.02 eV, respectively, in spin (↑) direction. However, in spin (↓) direction, the values of energy band gaps are 2.05 and 1.82 eV for LiCoO₂ and LiNiO₂, respectively. The total magnetic moment \({m}_{tot}\) values for LiCoO₂ are higher, compared to LiNiO₂. Unfilled d-orbitals (Co \(-{3d}^{7}\) and Ni \(-{3d}^{8}\)) in transition metals are responsible for highest portion of \({m}_{tot}\). Based on \(n(\omega )\) values of LiXO₂ (X = Co, Ni) delafossite compounds, we can infer that these compounds are optically active materials, as their values are between 1.0 and 2.0. The \({\varepsilon }_{2}(\omega )\) spectra demonstrate that LiXO₂ (X = Co, Ni) compounds are auspicious entrants for solar cell appliances working in visible and UV regions. It can be inferred from the computed results that these crystalline materials are promising candidates for prospective photovoltaic appliances.