Fabrication of Cu2ZnSn(S,Se)4 Thin Films by Sulfurization of Precursor Evaporated from Cu2ZnSnSe4 Compound

Cu2ZnSn(S,Se)(4) thin films and solar cells are prepared by sulfurization of the precursors evaporated from Cu2ZnSnSe4 compound and their properties are investigated. Each materials of Cu2ZnSnSe4, Zn + Sn + Se, and NaF + Se are sequentially evaporated on Mo/soda lime glass substrate. The substrate temperature of Zn + Sn + Se evaporation is changed from 300 to 550 degrees C. These precursors are crystallized by sulfurization in sulfur/tin mixing atmosphere for 30 min at 550 degrees C. From the Raman spectra, two kind of precursor formations such as Cu2ZnSnSe4 and Cu2SnSe3 by changing the substrate temperature are confirmed. The high V-oc of 574 mV is obtained in the sample which sulfurized from Cu2SnSe3 precursor, and it is higher than the sample which sulfurized from Cu2ZnSnSe4 precursor (V-oc = 449 mV). The finding of this study is to have revealed a new crystallization process of fabrication of the Cu2ZnSn(S,Se)(4) thin film.