UV-Vis Sintering Process for Fabrication of Conductive Coatings Based on Ni-Ag Core-Shell Nanoparticles

Abstract

The UV-Vis sintering process was applied for the fabrication of conductive coatings composed of low-cost nickel-silver (Ni@Ag) nanoparticles (NPs) with core-shell structures. The metallic films were formed on a plastic substrate (polyethylene napthalate, PEN), which required their sintering at low temperatures to prevent the heat-sensitive polymer from destroying them. The UV-Vis sintering method, as a non-invasive method, allowed us to obtain metallic coatings with good conductivity at room temperature. In optimal sintering conditions, i.e., irradiation with a wavelength of 350-400 nm and time of 90 min, conductivity corresponding to about 30% of that of bulk nickel was obtained for the coatings based on Ni@Ag NPs.

Keywords: UV-Vis sintering; conductive coatings; nickel–silver core–shell nanoparticles.

Figure 1

Scheme of the fabrication of the conductive coatings based on Ni@Ag NPs by using UV-Vis sintering process.

Figure 2

The characterization of the dispersion of the Ni@Ag NPs: size distribution (A), UV-Vis spectrum ((B), dotted line), SEM image (C), and EDX spectrum (D). The UV-Vis spectrum of the dispersion of the Ni NPs ((B), solid line).

Figure 3

Examples of optical microscopy images of deposited ink coatings based on Ni@Ag NPs after the drying process (80 °C, 15 min): (A) without a wetting agent; (B) with BYK 348 at 0.05%.

Figure 4

The dependence of the resistivity of coatings formed from Ni@Ag ink after the UV-Vis sintering process (A) at a time of 90 min in the wavelength range 300–700 nm and (B) at a wavelength of 400 nm at various sintering times.

Figure 5

FTIR spectra of CMC films: dried at room temperature (red); dried at 80 °C and irradiated with UV for 90 min (green).

Figure 6

The comparison between the FTIR spectra of CMC (grey) and Ni@Ag NP (pink) coatings after drying at room temperature and films based on Ni@Ag NPs after drying at 80 °C (15 min) and UV-Vis sintering for 90 min (blue).

Figure 7

Examples of SEM images obtained for coatings based on Ni@Ag NPs after drying (A) and the UV-Vis sintering process at the optimal time conditions time—90 min and wavelength of 400 nm (B).