Structural and electrical characteristics of printed silver and palladium nanoparticle networks
CB van den Berg, M Topic†, B Magunje, DT Britton, M Harting
In this study, silver and palladium nanoparticulate inks with different
metal-binder ratios were screen-printed onto a paper substrate. The
printed layers comprised the metal nanoparticles and an ethyl
cellulose binder. The layers are not typical metal composites due to the
low concentration of binder and high porosity. The electrical sheet
resistivity of each particle concentration was measured, and the data
fitted using the scaling law of percolation theory and the general
effective media (GEM) equation. The percolation parameters, i.e. the
percolation threshold and the critical exponent, for each system were
determined from the fits and compared. The percolation threshold for
the palladium layer (39.8 wt%) was lower than that found for the
silver layer (44.9 wt%). The critical exponents determined for the
palladium and silver layers were both lower than the universal value
for three-dimensional percolation systems. Microscopy observations
indicate that the difference in the percolation threshold for the two
layers can be attributed to variations in their microstructure.
Keywords: printed electronics, nanotechnology, nanoparticulate inks, silver,
palladium.