Shapes andmorphologies of inkjet-printed nanosilver dots on glass substrates

We investigated the effects of surface wettability, substrate temperature, and overprinting on the shapes and morphologies of dried and sintered inkjet-printed dots of nanosilver suspensions. The surface wettability was modified by two different plasma surface treatments: C4F8 plasma treatment for hydrophobic surface and O-2 plasma treatment for hydrophilic surface. The substrate temperature was varied from 25 to 85 degrees C with an interval of 20 degrees C. In order to change the dot thickness, dots were overprinted up to three times after complete drying of the ones previously printed. Printed dots were sintered for 1 h at 210 degrees C. The shapes and morphologies of dried dots including both single and overprinted dots were strongly influenced by the surface wettability of the substrate. The cross-sectional profile was more convex on the hydrophobic surface at lower substrate temperature, but stack-like morphologies of overprinted dots were obtained on both surfaces at higher substrate temperature due to the fast evaporation of solvent and coffee ring effect. Dots on hydrophilic surfaces experienced more shrinkage after sintering, and the shrinkage ratio of sintered dots tended to decrease with an increase in the number of overprints. The microstructure of sintered dots showed that nanoparticle clusters were more closely packed on hydrophobic surfaces. Copyright (C) 2010 John Wiley & Sons, Ltd.