Synergistic capping strategy for oxidation-resistant copper nanoparticles enables low-resistivity printed flexible electronics

The synthesis of oxidation-resistant, uniformly dispersed copper nanoparticles (Cu NPs) is a critical challenge in developing high-performance, low-cost conductive inks for printable flexible electronics. Here, we provided a novel synthesizing strategy for the Cu NPs through deallying Mg₈₀Cu₁₀Y₁₀ metallic glass precursor with mixed capping agents of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG). A PEG/PVP mass ratio of 1:2 yields Cu NPs with a mean diameter of ∼87.7 nm, exhibiting exceptional anti-oxidation and dispersion stability in ethanol for over 20 days. A synergistical protection mechanism is revealed that PVP mainly confers steric hindrance to prevent aggregation, while PEG establishes a compact oxygen-impermeable layer on the particle surface. When formulated into conductive inks, these nanoparticles (NPs) were screen-printed onto flexible polyimide substrates, achieving a post-sintering resistivity as low as 48 μΩ·cm. This study provides a robust and scalable route for cost-effective preparation of high-performance nano-copper inks for printable flexible electronics.