(Invited) Effects of Annealing Process on Morphology, Crystal Structure, and Photoelectrical Properties of CZTS Thin Films

In this study, Cu₂ZnSnS₄ (CZTS) thin films were directly formed on FTO glass substrates by a simple ethanol-thermal method, and the films were annealed at 823K under different atmosphere environments. Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), and photoelectrical measurements were used to investigate effects of annealing parameters in surface morphology, chemical compositions, and crystal structures of the thin films as well as photoelectrical properties, respectively. All the thin films were smooth and compact, but their color and micro-topography were different through different annealing atmosphere. The addition of sulfur during the annealing process is necessary to tailor sulfur concentration in the films and the crystallization of CZTS phase. Furthermore, the films exhibited p-type semiconductor characteristics, which is desirable for their applications in thin films solar cells.