Study on the Optimization of Cu-Zn-Sn-O to Prepare Cu₂ZnSnS₄ Thin Film via a Nano Ink Coating Method

To reduce the formation of the impurity phase, a buffer volume can be used to expands and smooths the surface of Cu₂ZnSnS₄(CZTS) thin film. In this study, a Cu-Zn-Sn-O(CZTO) precursor was synthesized through the process of coprecipitation-calcination-ball milling-spin coating. The influence of pH, temperature, and PVP on the constituent of hydroxides was investigated in the process of coprecipitation. Cu-Zn-Sn-O with appropriate compositions could be obtained by regulating the temperature and preservation time of the calcination stage. After ball milling to form a nano ink, and then spin coating, SEM images proved the generation of CZTO precursors, which effectively promoted the formation of Cu₂ZnSnS₄ thin films. Finally, the phase, microstructure, chemical composition, and optical properties of the Cu₂ZnSnS₄ thin films prepared by sulfurized annealing CZTO precursors were characterized by EDX, XRD, Raman, FESEM, Hall effect, and UV methods. The prepared CZTS thin film demonstrated a band gap of 1.30 eV, which was suitable for improving the performance of CZTS thin film solar cells.