Surface energy and polarity of treated indium-tin-oxide anodes for polymer light-emitting diodes studied by contact-angle measurements

Abstract

We present contact-angle hysteresis and surface energy of differently treated indium-tin-oxide (ITO) thin films obtained from contact angles for liquids with different polar character. We find that the hysteresis and the polar and dispersion component of the surface energy depend strongly on the surface treatments. Oxygen-plasma treatments induce the highest polarity and the highest total surface energy, and we suggest that this improves the interface formation with polymers, and therefore, the performance of light-emitting diodes. We discuss the results in relation to the ITO surface roughness and chemical heterogeneity modified by the different treatments. © 1999 American Institute of Physics.