Cu2ZnSnS4 (CZTS) films were synthesized by wet chemical processes and then annealed under controlled argon atmosphere. This study was conducted in two stages. In the first stage, the precursor solutions were prepared in three levels of sulfur content. These films were deposited from the precursor solutions and annealed at 250 ℃ for 1 hour. The results showed that the CZTS film deposited from the sulfur content S3.0 had the better optoelectronic properties as compared to its counterparts. The optical energy gap value was 1.52 eV, and the absorption coefficient was greater than 104 cm-1, while it had the smallest resistivity of 4.68 Ω cm.In the second stage, the annealing temperature was set at 300 and 350 ℃ to identify how it would affect these film’s structures and optoelectronic properties. The film annealed at 250 ℃ was introduced for the purpose of comparison. It was found that when the annealing temperature increased from 250 to 350 ℃, all the films were of the Kesterite structure, and no secondary phase was observed. As demonstrated, the thermal compressive stress generated as the annealing temperature increased could change the appearances of the films. More particularly, the crackled surface was changed to one with hillocks. The films optical direct energy gap values were increased from 1.52 to 1.68 eV and the resistivities were increased from 4.68 to 124.49 Ω cm. Each of the CZTS films had absorption coefficients greater than 104 cm-1.
