Síntesis de películas delgadas de ZnS por CBD para uso como capa buffer en celdas solares basadas en Cu2SnZnS4

ZnS thin films were deposited by CBD (chemical bath deposition) method using a solution containing thiourea and zinc acetate as sources of S and Zn and ammonium citrate as complexing agent. The samples were grown on soda lime glass substrates covered with a Cu2SnZnS4 (CZTS) thin film. Through an extensive parameter study carried out varying the main deposition parameter in a wide range, conditions were found to grow ZnS thin films with suitable properties to be used as buffer layer in Cu2SnZnS4 based solar cells.The ZnS films were characterized using techniques such as spectrofotometry, X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD measurements revealed that ZnS films with thicknesses lower than 200 nm grow with amorphous structure; however, samples with thicknesses higher than3 nm present crystalline structure corresponding to the ZnSO8H8 (zinc sulphohydroxide) phase, indicating that the film formed is really a mixture of ZnS and Zn hydroxides, known generically in the literature as Zn(S,OH).