Silver–Copper Alloy Nanoinks for Ambient Temperature Sintering

Abstract

There is an increasing need to reduce the silver content in silver-based inks or pastes and achieve low-temperature sintering for scalable and low-cost production of printed wearable electronics. This need depends on the ability to control the metal composition and the surface properties of the nanoinks. Alloying silver with copper provides a pathway for meeting the need in terms of cost reduction, but little is known about the composition controllability and the low-temperature sintering capability. We report herein a scalable wet chemical synthesis of bimetallic silver–copper alloy nanoinks with room temperature sintering properties. The bimetallic alloy nanoparticles with a controllable composition can be formulated as stable nanoinks. The nanoinks printed on paper substrates are shown to sinter under room temperature. In addition to composition dependence, the results reveal an intriguing dependence of sintering on humidity above the printed nanoink films. These findings are assessed based on theoretical simulation of the sintering processes via surface-mediated sintering and interparticle necking mechanisms in terms of nanoscale adsorption, adhesion and diffusion, and surface free energies. Implications of the findings for room temperature fabrication of wearable sensors are also discussed.

Plasmonic Ag/Cu/PEG nanofluids prepared when solids meet liquids in the gas phase

“…This peculiarity has been widely recognized in the wet chemistry and biochemistry community that has dealt with aqueous solutions and investigated the tunable plasmonic properties of Ag and Cu NP mixtures, and nanoalloyed AgCu NPs. [29][30][31] Routinely, PEG has been used as a capping agent to reduce the NP agglomeration. However, the combination of Ag and Cu seems to have been overlooked by the sputter community that has dealt with non-aqueous systems, often using PEG as a host liquid.…”

Screen-Printable Cu–Ag Core–Shell Nanoparticle Paste for Reduced Silver Usage in Solar Cells: Particle Design, Paste Formulation, and Process Optimization

“…Because of this, there is a serious industry demand for a suitable, low-cost silver replacement. Although copper has drawn tremendous attention as a low-cost silver replacement due to its low cost and high electrical conductivity, − , there have been few successes reported as it easily oxidizes in air. , As a result, copper replacements require an inert atmosphere such as N 2 or Ar to prevent them from oxidation, which complicates the fabrication processes and saddles industrial applications with significant additional costs. Copper can cause other issues due to its high diffusion in silicon.…”

“…Silver is widely used in pastes suitable for printing and soldering, thus enabling low cost of fabrication via approaches such as screen printing. , Unfortunately, silver has a substantial material cost and thus can be a significant contributor to the overall cost when used as printed conductors for electronic applications. − More importantly, silver is highly demanded across several industries, one of the most significant being the photovoltaic industry. As a result, due to the projected increase in photovoltaic demand globally, the cost of silver could increase by almost 1 order of magnitude by 2040 .…”