Grain coalescence of inkjet-printed Ag patterns studied by means of magnetotransport measurements

We fabricate and characterize silver (Ag) line patterns obtained by means of the drop-on-demand inkjet printing technique. We use a very simple and cost-effective reduction reaction of silver nitrate (AgNO3) aqueous solution deposited on different substrates, namely flexible polyimide (Kapton®), alumina and insulating glass ceramics (Macor®). We analyze magnetotransport and microstructural properties of the inkjet-printed Ag patterns. In all cases, well-defined line shapes and conductive patterns are obtained with resistivity values of about 40,30 and 90 μΩ cm for Ag on Kapton, alumina and Macor, respectively, which are nearly 25,20 and 60 times higher than bulk silver resistivity. These high resistivity values are due to the poor homogeneity and density of granular structures, confirmed by morphological SEM images. From the comparison with bulk Ag resistivity curve and the analysis of magnetoresistance, we find that intergrain resistance at low temperature (4K) is negligible for Ag on Kapton and alumina, while it represents a 10% fraction of Ag intragrain resistivity for Ag on Macor. This indicates that intergrain connectivity itself is not a serious issue, while grain packing and density are. Hence, in view of obtaining highly conducting Ag patterns, alumina appears to be the best substrate choice among the three investigated ones and there exists an edge of improvement in terms ofgranular structure.