Materic’s DirectSilver™ nanowires are delivered suspended in 2-propanol (isopropyl alcohol or IPA). The ink should appear as a grey colored and homogeneous solution. The ink needs to be stored airtight in a cool and dark environment, away from all sources of light, especially direct sunlight to prevent degradation of the silver nanowires (AgNW). The DirectSilver™ ink is shipped ready for application on the relevant surface, although the ink should be shaken well before each usage. The Materic team has found that its AgNW is suitable for different fabrication methods. In particular, the research team achieved optimal conductivity and transparency with both the nozzle spraying casting and the spin coating methods.

Materic’s DirectSilver™ nanowires are developed to 30nm in diameter and 15um in length with aspect ratio of 500. To achieve and maintain these desirable material dimensions, Polyvinylpyrrolidone (PVP) is used during the silver nanowire growth process as a stabilizer and capping agent. PVP is a non-toxic, chemically inert, and biodegradable polymer that is safe to use in humans. It is widely found in other applications such as food, cosmetics, and pharmaceuticals. The presence of the PVP, however, is not conducive for the AgNW to be optimally conductive and transparent.

During the AgNW development and optimization process, the Materic team discovered that, to achieve the full conductivity potential of the AgNW ink, a washing step is called for to remove the PVP. It is common practice for whatever surface applied with the AgNW ink to undergo an annealing process to reach optimal conductivity. Materic recommends ethanol soaking and rinsing of the AgNW applied surface before the annealing step to remove the PVP for the best performance.

Detailed washing instructions to remove the PVP:

1. Cast the AgNW ink to the application surface.

2. Soak the surface in ethanol for 5 minutes.

3. Rinse off the surface with ethanol at the end of the soaking step.

4. Anneal the surface under 135C for 30 minutes.

5. The surface is ready for use.

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