Effects of copper concentration on the properties of Cu2CoSnS4 thin films co-electrodeposited on the FTO substrate.

The optimization of the factors influencing the co-electrodeposition method makes it extremely efficient in the production of thin films formed by multiple elements. This work presents the synthesis of Cu₂CoSnS₄ (CCTS) thin films by the simultaneous electrodeposition of Co, Sn, Cu, and S elements on the FTO substrate using tartaric acid (HT) as a complexing agent. To study the influence of copper concentration on the physicochemical properties of CCTS, these films were deposited at a co-electrodeposition potential of − 900 mV for concentrations [Cu²⁺] ranging from 0.015 to 0.030 M (vs. saturated calomel electrode (SCE)). After a sulfurization step in a quartz tube at 500 °C under an argon flow for one hour, the samples formed are analyzed by different techniques: X-ray diffraction technique showing characteristic peaks relating to planes (112), (204), (312) (400), and (004) of the CCTS phase, as well as the characteristic peaks located at 290 cm⁻¹ and 325 cm⁻¹ with Raman spectroscopy, and then the effect of copper concentration on the optical properties was identified by UV–Visible spectrophotometry which showed that the optical-gap values are decreased from 1.68 to 1.48 eV when the Cu concentration was varied from 0.015 to 0.030 M. [ABSTRACT FROM AUTHOR]