First-principles calculations to investigate structural, electronic, elastic and optical properties of Ag2ZnSnS4 and Ag2ZnSnTe4 alloys
摘要
The structural, electronic, and optical characteristics of Ag2ZnSnS4 and Ag2ZnSnTe4 were comprehensively investigated to assess their potential as semiconductor materials using density functional theory (DFT) calculations. Structural optimization calculations confirm that, for both compounds, the kesterite phase is the most stable configuration. The electronic structure was computed using both the generalized gradient approximation with the Perdew–Burke–Ernzerhof functional (GGA-PBE) and the more accurate screened hybrid functional (HSE06) to obtain reliable band-gap prediction. For the stannite phase, the calculated band gap values are 0.534 eV (GGA) and 1.509 eV (HSE06) for Ag2ZnSnS4, and 0.138 eV (GGA) and 0.452 eV (HSE06) for Ag2ZnSnTe4. In the energetically preferred kesterite phase, the corresponding band-gap values are 0.673 eV (GGA) and 1.676 eV (HSE06) for Ag2ZnSnS4, and 0.466 eV (GGA) and 0.832 eV (HSE06) for Ag2ZnSnTe4. The results obtained using the HSE06 hybrid functional show good agreement with available experimental data, confirming the semiconducting nature and optoelectronic potential of these quaternary chalcogenides. In addition to the electronic properties, the optical response of both materials was systematically analyzed by evaluating the real and imaginary parts of the dielectric function, along with key optical constants such as the refractive index and reflectivity. Overall, this comprehensive investigation highlights the promising performance of Ag2ZnSnS4 and Ag2ZnSnTe4for future photovoltaic and optoelectronic applications.