Nanowire silver ink: highly conductive right out of the printer

January 18, 2017 // By Julien Happich
In a recent study, researchers from Duke University experimented with different types of pure silver-based conductive inks to assess how the shape of the silver nanoparticles they dispersed into water would impact the conductivity of dried up inked patterns.

Their findings published in the ACS Applied Materials and Interfaces journal in a paper titled "The Effect of Morphology on the Electrical Resistivity of Silver Nanostructure Films" are unambiguous.

To compare the different ink-jet printer-ready "inks", the researchers sintered thick films of silver nanowires (Ag NWs) of two different lengths, nanoparticles (Ag NPs) and microflakes (Ag MFs) at temperatures ranging from 70 to 400°C.

Although, the nanowires were expected to be more conductive due to their shape more readily intertwined when printed on paper, the silver nanowire-based inks were not only much more conductive than comparable inks with a similar weigh-ratio of round silver nanoparticles or flat silver microflakes, they didn't even require a high temperature sintering step to beat all benchmarks.

Sintering the film of long Ag NWs at only 70°C (a temperature compatible with regular paper and plastic substrates) yielded a resistivity of 1.8×10 –5 Ω cm, making those films 4000 times more conductive than films made from Ag NPs and still more conductive than those same films sintered at 300ºC.

What they also found out is that adding 10 wt % of silver nanowires to a film of silver nanoparticles was enough to improve conductivity 400 folds.

This would make such inks readily usable on most substrates, without any post-processing.

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