Advanced Computational Insights Into Cs₂NaScX₆ (X = Cl, Br) ₆ Double Perovskites: Structural Stability, Elastic Properties, and Optical Characteristics for Next-Generation Photovoltaics

We investigate the comprehensive analysis's structural, electronic, optical, and elastic properties of Cs₂NaScX₆ (X = Cl, Br) double perovskites using density functional theory (DFT) implemented by the WIEN2k code. The results show that both compounds are in cubic phases. The calculated tolerance factors show both are stable compounds. The computed optimized lattice parameters are Cs₂NaScX₆ (X = Cl, Br) are 10.72 Å and 12.01 Å, respectively. Employing a modified Becke–Johnson (mBJ) potential electronic nature shows that both compounds are in semiconductor nature, that is, 3.138 eV and 3.977 eV. The calculated elastic constant and perimeters show the Cs₂NaScX₆ (X = Cl, Br) are mechanical stables and also ductile and anisotropic nature. The optical properties described the range of photon energies from 0 to 10 eV, revealing pronounced absorption within the visible spectrum, highlighting their considerable promise for transformative innovations in photovoltaic technology. These double perovskites exhibit superior absorption characteristics compared to their Cs₂NaScX₆ (X = Cl, Br) analogues, thus laying the groundwork for significant advancements in solar energy conversion and photovoltaic applications.