Direct synthesis and inkjetting of silver nanocrystals toward printed electronics

Abstract

Monolayer-protected silver nanoparticles were directly synthesized in a highly concentrated organic phase (>2 M) and then printed into conductive lines on polyimide by a drop-on-demand inkjet printer. The fully organic phase system contains silver nitrate as a silver precursor, n-butylamine as a media dissolving silver salt, dodecanoic acid as a capping molecule, toluene as a solvent, and sodium borohydride as a reducing reagent. Even using only generic chemicals, monodispersed silver nanocrystals with size of 7 nm were easily synthesized at the 100 g scale in a 1 litre reactor. Hydrocarbon monolayer-protected silver nanocrystal showed excellent dispersion stability even at metal content >70 wt%. The silver ink with metal content of 33 wt% had a viscosity of 5.4 cP and surface tension of 25 dyn cm −1 . The silver ink was successfully inkjetted on variable substrates and then metallized at 250 • C. The metallized silver patterns exhibited very low specific electrical resistance (6 µ cm)

Metal-based Inkjet Inks for Printed Electronics

“…As to the formation of Ag NPs in organic solvents, ethanol [68] and N,N-dimethylformamide [52,69] can also function as reducing agents, but in most cases, formation of Ag and Cu NPs in organic solvents requires the addition of a dedicated reducing agent [26,[70][71][72][73][74][75].…”

“…Dispersions of Ag NPs with sizes in the range of 10-30 nm and metal concentration of about 20 % were prepared by reduction of Ag 2 O with gum arabic, which is also a stabilizing agent [136]. Dodecanoic acid-protected Ag NPs (~7 nm) with a concentration of about 21 % were synthesized in toluene [70]. Even more concentrated aqueous dispersions of Ag NPs (up to 40 %) with particle sizes of less than 10 nm were fabricated with the use of ammonium salt of poly(acrylic acid) with molecular weight of 15,000 as a stabilizing polyelectrolyte [8].…”

Inkjet Printing and Alternative Sintering of Narrow Conductive Tracks on Flexible Substrates for Plastic Electronic Applications

“…This process is called sintering and takes place with small particles within the medium and at room temperature. Therefore, the nanoparticles have to be protected by a shell to prevent agglomeration in solution and to obtain a stable colloidal dispersion, as schematically depicted in Figure 6 (Lee et al, 2006). In non-polar solvents usually long alkyl chains with a polar head, like thiols, amines or carboxylic acids, are used to stabilise the nanoparticles (Perelaer et al, 2008a).…”

Electrostatic deposition of nanothin films on metal substrate

“…3. Gold or silver nanoparticles were deposited as nanowires for nanoelectronic applications [13,[35][36][37][38]. 4.…”