Effect of oxygen plasma on ITO surface and OLED physical properties

In this study, we treated the surface of indium tin oxide (ITO) with oxygen plasma. In doing so, ITO thin films were exposed to oxygen plasma. This treatment was performed with plasma oxygen at 4, 6, and 8 min. The ITOs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and ultraviolet-visible (UV–vis) spectroscopy. These characterizations showed that the structure and transparency were only slightly changed by the treatment. However, the plasma treatment improved the surface morphology and changed the thickness and electrical properties of the ITOs. The surface roughness of the ITOs was reduced from 2.34 to 0.899 nm by the treatment. With an 8-min plasma treatment, the strength of the sheet without ITO treatment increased from 12.61 to 13.97 Ω/□. The organic light-emitting diodes (OLEDs) with glass/ITO/PEDOT:PSS/Alq3/Al structure were fabricated. Characterization of the OLEDs showed a decrease in threshold voltage (from 5.7 to 3.53 v), a decrease in resistance, and an increase in irradiance intensity due to plasma treatment.