Ligand‐Engineered Cu@Ni Core‐Shell Nanoparticles with Excellent Performance for Printed Electronics

Employing Cu nanoparticle (NP) inks to replace Ag inks for printing conductive patterns is a highly promising manufacturing technology in advanced electronics, due to the cost‐effective characteristic and electrochemical migration resistance. However, the easy oxidation in air and high‐temperature sintering conditions present significant challenges for the preparation of high‐performance Cu NP inks and the fabrication of long‐lasting printed electronic devices. To address this, based on the ligand exchange strategy, low‐cost, uniformly sized, and stable Cu@Ni core‐shell NPs are prepared via a one‐pot in situ‐reduced method. Then, the influences of varying Ni dosages on the surface ligand structures are investigated. Notably, the dense Ni shell passivates the Cu@Ni NPs, endowing them with excellent oxidation resistance, allowing storage in air for a month without deterioration. Through experiments and molecular dynamics (MD) simulations, the low‐temperature sintering mechanisms of the Cu@Ni NPs are systematically elaborated. Compared with Cu NPs, the interfacial diffusion of Cu–Ni core‐shell structures and ultrafine particles (UFPs) significantly promotes the sintering of NPs. A low resistivity (18.6 µΩ cm) of Cu–Ni thin films is further achieved via low‐temperature sintering (200 °C) and UV nanosecond laser sintering. Finally, large‐area and functionalized Cu–Ni conductive patterns are fabricated on flexible substrates, demonstrating great potential in advanced printed electronics.