Theoretical Insights through DFT into AgBiS₂ Thin Films Absorber for Photovoltaic Applications

AgBiS₂ has emerged as a promising absorber material for thin-film solar cell applications due to its earthabundant, non-toxic composition and tunable optical bandgap (Eg) (0.8–1.32 eV), making it suitable for low-cost and scalable production. This study comprehensively investigates the suitability of AgBiS₂ absorber for solar cells, emphasizing its structural, optoelectronic, and photovoltaic performance. Using density functional theory (DFT), we explore the electrical and optical properties, including Eg, absorption coefficient (α), dielectric constant, and refractive index. The result shows a very high ‘α’ of the order of ~106, and Eg (direct/indirect) calculated by MGGA and HSE method 1.18/0.63, and 1.55/0.99 respectively, which is very close to the experimental value ~1.0 eV. These insights highlight the potential of AgBiS₂ as a versatile absorber material, paving the way for advancements in thin film solar cell technologies.