Nanocomposites and nanomaterials

Silver nanoink for printable electronics
Dobrozhan O.A.1, Huzenko O.I.1, Kurbatov D.I.1, Opanasyuk A.S.1
1 Department of Electronics and Computer Technology, Sumy State University. 2, Rymskogo-Korsakova st., 40007 Sumy, Ukraine.
E-mail: o.dobrozhan@ekt.sumdu.edu.ua

Herein we present the technological procedure to develop the electrically conductive patterns onto the flexible substrates by printing low-cost, eco-friendly silver nanoink by using the piezoelectric drop-on-demand inkjet technology. 
In order to synthesize the silver nanocrystals, silver nitrate (AgNO3, purity > 99 %), polyacrylic acid ((C3H4O2)n, MW = 1800 g/mol), triethanolamine (C6H15NO3, purity > 98 %) were dissolved in the distilled water and stirred for 2 hours. Afterwards, the suspension was heated to the 70 oC for 20 min in order to accelerate the reaction rate. Finally, the nanocrystals were washed with the isopropanol through centrifugation step and subsequently dried at 70 oC for 60 min under the ambient atmosphere. The printable nanoink was obtained by dissolving 500 mg of dried Ag nanocrystals in 9 ml of distilled water and 1 ml of ethylene glycol accompanying with an ultrasonication for 5 min. The described synthesis protocol was adapted from literature [1].
To print the electrical scheme onto the photo paper was used Epson Stylus TX190 printer with the rechargeable cartridges. The prototype of the circuit board containing conductive patterns is presented on Fig. 1. The increase of printing cycles from 1 to 3 reduced the electrical resistance of circuit patterns from mega to hundreds Ohms. Additional annealing treatments at 100 oC for 20 min led to the better adhesion and lower resistance of 40 Ohm.

Fig. 1. The printed conductive electronic scheme onto the photo paper by using the drop-on-demand inkjet technology.

This approach opens the new possibilities to print the silver electrodes for micro-, optoelectronic devices, in particular for the solar cells.

1.	Russo A., Ahn B., Adams J, et al. Pen-on-Paper Flexible Electronics // Adv. Mater.-2011.-23.-P. 3426-3430.