Characterization of Cu2ZnSnS4 Thin Films Prepared by Solution-based Deposition Techniques

Cu2ZnSnS4 (CZTS) compound semiconductor has attracted considerable interest for use in low-cost thin-film PVs because of its earth-abundant constituents, optimal band gap, and high absorption coefficient. In this paper, CZTS thin films have been successfully prepared on soda-lime glass substrates by solution-based deposition techniques. The CZTS nanocrystals were synthesized by hot-injection method from copper (II) acetylacetone, zinc (II) acetate, tin (II) chloride and sulfide powder in an argon protection atmosphere. The as-synthesized nanocrystals were characterized by transmission electron microscopy (TEM). The structure, morphology, composition, and optical properties of the CZTS films were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and UV-vis spectrometry. The XRD analysis demonstrated that CZTS thin films possessed a single- phase kesterite structure and no secondary phases were observed in the XRD diffraction pattern. The SEM micrographs showed the CZTS films were uniform, dense and had almost no voids. The chemical composition of CZTS films was nearly stoichiometric. The band gap was about 1.57 eV and the annealed CZTS thin films are very suitable for the absorber of solar cells.