Synthesis and characterization of co-electroplated Cu₂ZnSnS ₄ thin films as potential photovoltaic material

Cu₂ZnSnS₄ thin films have been successfully prepared by a novel synthesis process that involves a single step deposition of Cu ₂ZnSnS₄ followed by a post-annealing treatment at 550 °C for 60 min in the atmosphere of N₂H₂S (5%). The microstructure, morphology, composition and optical property of the film have been investigated in detail. It is found that the Na₂S ₂O₃5H₂O concentration in the solution has a significant effect on the Cu₂ZnSnS₄ thin films. X-ray diffraction data indicates that the annealed Cu₂ZnSnS₄ thin films have a kesterite structure with preferred orientation along the (1 1 2) plane. Uniform and compact topographies are observed in some annealed films. From the energy dispersive X-ray spectroscopy analysis, it can be seen that Cu-poor and Zn-rich Cu₂ZnSnS₄ thin films have been obtained. The direct band gap energy of the film is about 1.5 eV.