First-principles calculations to investigate the electronic and optical properties of Cu2ZnSnS4 with Ag and Se codoping

Abstract

In recent years, Cu2ZnSnS4 has drawn great attention owing to its outstanding performance, such as nontoxic and earth-abundant elements, suitable band gap, and high absorption coefficient. In the present study, we have explored the impact of the partial substitution of Cu and S with Ag and Se on the optoelectronic properties of Cu2ZnSnS4. The results suggest that the calculated lattice constants of A2ZnSnX4 (A = Cu, Ag; X = S, Se) with the PBE functional are in good agreement with the experimental values. Furthermore, the band gap obtained by the PBE0 functional for A2ZnSnX4 is consistent well with the experimental data. (Cu0.5Ag0.5)2ZnSn(S0.5Se0.5)4 displays an optimum direct band gap with 1.40 eV and shows wide and high absorption coefficient. Our work demonstrates that the studied compound is proposed to be a promising candidate for environmentally friendly photovoltaic material.