Synthesis and characteristic of Cu₂ZnSnS₄ thin film prepared by appropriate non-stoichiometry precursor

Non-stoichiometry sulphur-containing precursors were studied to picture its connection to the formation of kesterite Cu₂ZnSnS₄ (CZTS) phase. The precursors were prepared from metal (Cu-Zn-Sn) chlorides with ethanol as solvent and 2-mercaptopropioninc acid as capping ligand. Mol ratio of S/Cu 4.4 was observed as the limit of non-stoichiometry. Confirmed by XRD characterization, the employment of sulphur in higher concentration resulted in the formation of secondary phases with a porous morphology. Further, a modification in holding time of annealing treatment was successfully improved the crystallinity of the CZTS film. The SEM micrograph was showed the formation of well-growth CZTS grains with size ∼ 1.5 μm. However, porosity was still encountered at the surface film as indication of insufficient growth processes (heat treatment). The energy band characteristic of the film is 1.4 eV, determined by extrapolating the gradient line of (αhυ)² vs hυ (photon energy). The route presented in this paper offers alternative solution to synthesize CZTS semiconductor from ethanol-based precursor.