Surface treatment of indium tin oxide by oxygen-plasma for organic light-emitting diodes

We have carried out a systematic study to optimize the processing conditions in oxygen-plasma treatments on indium tin oxide (ITO) substrates used in organic light-emitting diodes (OLEDs). The treated ITO substrates were investigated by both contact angle measurements and X-ray photoelectron spectroscopy (XPS). It was found that oxygen-plasma treatment was quite effective in removing organic contaminants on the ITO surface, causing a reduction in contact angle. XPS revealed that the treatment led to a decrease in the surface content of carbon and an increase in the surface content of oxygen. Consequently, enhanced hole-injection, increased luminance efficiency and improved operational stability were observed in OLEDs having an ITO anode treated at the optimized conditions. (C) 2002 Elsevier Science B.V. All rights reserved.