Reaction kinetics of Cu_2-xS, ZnS, and SnS₂ to form Cu₂ZnSnS₄ and Cu₂SnS₃ studied using differential scanning calorimetry

Abstract

Differential scanning calorimetry experiments on mixed Cu_2-xS, ZnS, and SnS₂ precursors were conducted to better understand how Cu₂ZnSnS₄ (CZTS) and Cu₂SnS₃ form. The onset temperatures of Cu₂SnS₃ reactions and CZTS suggest that the ZnS phase may mediate Cu₂SnS₃ formation at lower temperatures before a final CZTS phase forms. We also found no evidence of a stable Cu₂ZnSn₃S₈ phase. The major diffraction peaks associated with Cu₂ZnSnS₄, and Cu₂SnS₃ (overlaps with ZnS, as well) began to grow around 380 °C, although the final reaction to form Cu₂ZnSnS₄ probably did not occur until higher temperatures were reached. An exothermic reaction was observed corresponding to formation of this phase. There was some variability in the onset temperature for reactions to form Cu₂SnS₃. At least 5 steps are involved in this reaction and several segments of the reaction had relatively reproducible energies.