First principles study on electronic and optical properties of Cu₂CoGeS₄ for photovoltaic conversion and photocatalytic applications

In this study, the structural, electrical, and optical characteristics of the Stannite Cu2CoGeS4 (CCGS) are investigated using first-principle calculations. Band gap energy is determined using both the mBJ + U and HSE potentials. Both methods yield to similar results (1.73 1.73 eV and 1.78 eV for the first and second, respectively and 1.78 eV for the first and second, respectively). Based on our numerical simulations, CCGS is a viable absorber material for solar systems due to its exceptionally high absorption coefficient (on the order of 10⁴ cm⁻¹). This work also determines other optical parameters such as the refraction index and the dielectric function. In addition, the SCAPS program was used to conduct a simulation of solar cells based on CCGS. Based on the computed values of the short-circuit current density J_sc, open-circuit voltage V_oc, Fill factor FF, and power conversion efficiency, CCGS is presented as a good choice for solar cells. We also explored the potential of CCGS for photocatalytic water splitting.