Study of Lithium-Based Double Perovskites Halides Li2AgBiZ6 (Z = Cl, Br, I) as Emerging Aspirant of Solar Cells and Energy Harvesting Applications

This Study uses density function theory calculations to examine the structural, elastic, optoelectronic, and thermal properties of lithium-based double perovskites Li2AgBiZ6 (Z = Cl, Br, I). The perovskite materials have good structural stability, as demonstrated by our computations, with a tolerance factor of 0.96, 0.95, and 0.93, respectively, and formation energy of -2.11, -1.89, and - 1.65 eV. The elastic constants of materials with cubic symmetry are examined to differentiate between their ductile or brittle nature, mechanical strength, minimum lattice thermal conductivity, melting point, Debye temperatures, and anisotropy. We utilized TB-mBJ potential to predict the electronic characteristics. Li2AgBiCl6, Li2AgBiBr6, and Li2AgBiI6 are semiconductors with indirect band gaps of 2.30, 1.83, and 1.20 eV, respectively. The low effective mass, as well as the binding energy of excitons, strong absorption in the visible region, and low reflectance, make them important materials for photovoltaic cells. Thermoelectric studies suggest moderate ZT values of 0.72, 0.63, and 0.58. Hence, the explored perovskite materials have promising features for solar energy generation and thermoelectric devices.