Electrochemical corrosion behaviors of ITO films at anodic and cathodic polarization in sodium hydroxide solution

The electrochemical corrosion behaviors of indium tin oxides (ITO) films were investigated by electrochemical methods in sodium hydroxide solutions. Cyclic voltammetries of ITO films at both anodic and cathodic polarization were carried out. Transmittance spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used for characterization of the optical transmittance, the corrosion morphology and identification of corrosion product. ITO film remained stable after anodic polarization. In contrast, serious corrosion occurred at cathodic polarization (approximately -1.3 V vs. saturated calomel electrode (SCE)). Meanwhile, optical transmittance decreased greatly. The results showed that some of Sn⁴⁺ in the ITO is reduced to the lower metal state in the form of hydroxides of Sn, which attached to the surface.