First Principles Study on Structural, Electronic, Optical and Mechanical Properties of Cu2BaSnS4 for Photovoltaic Applications

A first‐principles investigation of the quaternary chalcogenide Cu 2 BaSnS 4 is carried out using density functional theory within the generalized gradient approximation, incorporating Hubbard U corrections to assess its suitability as a solar cell absorber. Structural optimization confirms the trigonal phase, with lattice parameters Å and Å. The calculated electronic structure reveals an indirect band gap of eV. The orbital‐projected density of states indicates that the valence band is primarily composed of Cu and S orbitals, while the conduction band mainly originates from S and Sn states. The optical properties show strong absorption in the visible and ultraviolet regions, with absorption coefficients ranging from to cm, a static dielectric constant of and a peak refractive index of . Vibrational analysis confirms the dynamic stability of the material through the identification of infrared and Raman‐active modes at the point. Mechanical property calculations reveal a Pugh's ratio of , suggesting ductility and a Young's modulus of GPa, indicating moderate stiffness. These combined structural, electronic, optical, vibrational and mechanical characteristics establish Cu 2 BaSnS 4 as a promising candidate for high‐efficiency, earth‐abundant photovoltaic applications.