Effect of plasma treated ITO substrate on inkjet printing of conductive ink

In this paper, we investigate the effect to inkjet printing by modifying the surface condition of the substrate by plasma treatment as a possible processing technique to improve the printability and repeatability of ink-jet printed conductive ink on ITO coated substrate, and to identify the relationship between process parameters and property. Oxygen plasma surface treatment has been found to increase the surface energy of ITO coated substrates used in OLED. Uniform dots and lines were the desired print pattern. Surface energy of the treated film was quantified through the measurements of contact angles using a commercial conductive ink PEDOT-PSS. In addition, surface roughness and morphology of the treated ITO films were investigated to identify their effect on printability of the polymer. As surface treatment is also known to affect electrical properties of ITO, sheet resistance was studied. Results show that oxygen plasma improved the print quality dramatically and by varying plasma conditions used. Experimental data also showed that surface energy changed with storage time after treatment. Contact angle increased from 13deg to 50deg after 48 hours.