Search

Abstract: Sulfosalicylic acid (C7H6O6S) as a special additive was applied to favor the deposition of pure zinc sulfide (ZnS) nanocrystal thin films on ITO substrates from acidic solutions by potentiostatic technique with subsequent annealing. XRD, EDX, Raman, SEM and UV–vis–NIR analyses demonstrate that a proper concentration of C7H6O6S additive (0.2mM) in the electrolyte containing 20mM Zn2+, 20mM S2O3 2−, 0.375mM SO3 2− and 200mM LiCl can greatly contribute to the controllable growth of pure cubic ZnS film along (200) orientation at potential of −1.1V vs. SCE. The film possesses a uniform surface with an average crystallite size ca. 40.9nm, and a band gap ca. 3.68eV. Electrochemical studies indicate that C7H6O6S could adsorb on ITO surface and act as a hydrogen bond donor for free Cl−. The adsorption of C7H6O6S blocks some active sites used for the deposition of S, while the role of hydrogen bond donor promotes the deposition of Zn element by decreasing the concentration of [ZnCl4]2− and increasing the concentration and mobility of Zn2+ in electrochemical double layer. Consequently, the addition of C7H6O6S narrows the deposition potential gap of S and Zn elements in the range of −1.0 to −1.2V, thus resulting in their co-deposition to form pure ZnS. [Copyright &y& Elsevier]

Abstract: The effect of potassium hydrogen phthalate (C8H5KO4) as a special additive on the one-step electrodeposition of single-phase CuInS2 thin films from acidic solution (pH 2.5) was investigated in detail. The XRD, SEM and UV–vis–NIR characterization confirms that the addition of an adequate concentration of C8H5KO4 (23mM) to the electrolytic bath containing 12.5mM Cu2+, 10mM In3+, 40mM S2O3 2− and 100mM LiCl can contribute greatly to the controllable growth of pure chalcopyrite CuInS2 films with uniform surfaces and an ideal band gap of approximately 1.54eV. Complexation studies of C8H5KO4 with Cu2+ and In3+ in electrolytic solutions indicated that C8H5KO4 can complex Cu2+ more strongly than In3+ and move the electrode potentials of Cu2+ and In3+ near each other as determined by polarization analysis. Furthermore, the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analysis performed in a series of solution systems revealed a three-step reaction mechanism for CuInS2 deposition and considerable adsorption of C8H5O4 − and Cu(C8H5O4)+ to the cathode surface. This deposition shows that the synergetic effects of complexation and adsorption originated from the additive on the Cu2+ electro-reduction, thus promoting the co-deposition of copper, indium and sulfur in the form of single-phase CuInS2. [Copyright &y& Elsevier]