Effects of sulfurization temperature on the structural and optical properties of Cu₂CdSnS₄ thin films prepared by direct liquid method

Cu₂CdSnS₄ (CCTS) appears to be a promising absorber material for thin film solar cells and have been deposited on glass substrate by a direct liquid coating method. Effects of sulfurization temperature on the composition, morphology, structural and optical properties of CCTS have been investigated systematically. X-ray diffraction and Raman measurements reveal that the increase of temperature would lead to an improved crystallinity of CCTS and the secondary phase of Cu₂S confirmed by Raman spectrum can be suppressed by increasing annealing temperature. The grain size of CCTS thin films is demonstrated to be improved as the annealing temperature increases with slight S-poor and Sn-poor condition. All the thin films have estimated band gap in the range of 1.31–1.14 eV, which decreases almost linearly with the increasing temperature and can be well suited for use in photovoltaics and thermoelectricity.