Preparation and characterization of Cu₂ZnSnSe₄ and Cu₂ZnSn(S,Se)₄ powders by ball milling process for solar cells application

In this paper results on Cu₂ZnSnSe₄ and Cu₂ZnSn(S,Se)₄ powders, prepared by ball-milling process using elemental Cu, Zn, Sn, Se and S as the materials source and different milling times are presented. In addition, preliminary results on targets processed with different pressing pressures and submitted later to one post-thermal annealing are also presented. As an important result, it is found that kesterite compounds can be obtained by ball-milling technique under significantly lower time (2 h) than those reported in literature. The powders were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for structural and morphological studies, energy dispersive spectroscopy (EDS) and x-ray fluorescence (XRF) for compositional studies and Raman Spectroscopy technique for identifying the existence of possible secondary phases formation and defects. Photoluminescence measurements were carried out to study the radiative recombination, and the crystalline quality of powders. The pressed targets were studied by EDS, SEM and x-ray diffraction techniques. Our results are discussed in terms of using these powders in the processing of low-cost and high efficiency solar cells.