A Simple Process for Synthesis of Ag Nanoparticles and Sintering of Conductive Ink for Use in Printed Electronics

Abstract

Various-sized Ag nanoparticles capped with oleylamine were synthesized by means of a thermal decomposition process for low-temperature electronic devices. The Ag nanoparticles, which had diameter of 5.1 nm to 12.2 nm, were synthesized in incubation and ripening stages related to nucleation and growth. After the Ag nanoparticles were made into ink with a proper solvent, inkjet printing and thermal sintering methods were used to form a metal thin film with thickness of 100 nm. A type of thermal sintering related to percolation transformation and surface sintering was conducted at a temperature much lower than the melting point of bulk Ag. The electrical resistivity was examined with the aid of a four-point probe system and compared with the resistivity of bulk Ag, showing that the Ag film had much higher resistivity than bulk Ag. To improve the electrical stability and properties, we applied hexamethyldisilazane (HMDS) surface treatment to the substrate and dipped the as-deposited films into methanol. Both treatments helped to diminish and stabilize the resistivity of the printed conductive films.

A Review of Conductive Metal Nanomaterials as Conductive, Transparent, and Flexible Coatings, Thin Films, and Conductive Fillers: Different Deposition Methods and Applications

“…Results showed that using an appropriate amount of diacids led to sintering of Ag NPs that resulted in reducing the resistivity of the composite to as low as 5 × 10 −6 Ω cm, which was considered stable [30]. Researchers showed that the diameter of Ag NWs does not affect their electrical properties [20], whereas their length does affect their application in optoelectronic devices, as mentioned above. Madaria et al demonstrated that using Ag NWs with different lengths as a conductive network in polymer matrix and their application as electrodes in polymer solar cells influenced their performance.…”

“…HCl treatment not only avoided oxidation of Ag NWs, but also decreased the NW diameter, resulting in decreased resistance of the Ag NW thin film. The film deposited using the rod-coating method achieved 75% transmittance and a sheet resistance of 175 Ω/sq, with outstanding Liu et al proposed using Ag NW with different diameters (5.1 to 12.2 nm) mixed with hexadecane solvent to prepare ink (30 wt.% of Ag particles) to test the effect of Ag NW diameter on the resistance of the produced thin film [20]. A 100-nm-thick thin film was obtained by printing Ag NW ink, followed by sintering at a temperature much lower than the melting point of bulk Ag.…”

“…They showed that using a hexamethyldisilazane (HMDS) surface treatment followed by dipping the films into methanol could enhance the electrical properties of the thin film. Depositing patterned film of Liu et al proposed using Ag NW with different diameters (5.1 to 12.2 nm) mixed with hexadecane solvent to prepare ink (30 wt.% of Ag particles) to test the effect of Ag NW diameter on the resistance of the produced thin film [20]. A 100-nm-thick thin film was obtained by printing Ag NW ink, followed by sintering at a temperature much lower than the melting point of bulk Ag.…”

“…Their results showed that the electrical resistance of the ink-jet printed film was not affected by Ag NW size, and that increasing the sintering temperature decreased the resistance of the thin film. They showed that using a hexamethyldisilazane (HMDS) surface treatment followed by dipping the films Liu et al proposed using Ag NW with different diameters (5.1 to 12.2 nm) mixed with hexadecane solvent to prepare ink (30 wt.% of Ag particles) to test the effect of Ag NW diameter on the resistance of the produced thin film [20]. A 100-nm-thick thin film was obtained by printing Ag NW ink, followed by sintering at a temperature much lower than the melting point of bulk Ag.…”

“…Results showed that using an appropriate amount of diacids led to sintering of Ag NPs that resulted in reducing the resistivity of the composite to as low as 5 × 10 −6 Ω cm, which was considered stable [30]. Researchers showed that the diameter of Ag NWs does not affect their electrical properties [20], In cases of Ag NPs and NWs, solution-based methods are more popular with researchers, so a method for preparing a suitable solution (ink) composed of Ag NWs or Ag NPs with highly stable dispersion is needed. Ag-conductive ink is a mixture of Ag particles, solvents, surfactants, etc.…”