High-Concentration Synthesis of Sub-10-nm Copper Nanoparticles for Application to Conductive Nanoinks

• Published in: ACS applied materials & interfaces Vol. 7; no. 34; pp. 19382 - 19389
• Main Authors: Hokita, Yuki, Kanzaki, Mai, Sugiyama, Tomonori, Arakawa, Ryuichi, Kawasaki, Hideya
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.09.2015
• Subjects: air; ambient temperature; copper; ethylene glycol; heat; nanoparticles; nitrogen; solvents; low-temperature sintering; solution synthesis; copper nanoparticles; cu nanoink; sub-10-nm; alcohol-based solvents
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.5b05542

A simple, high-concentration (up to 0.6 M Cu salt) synthesis of sub-10-nm copper nanoparticles (Cu NPs) was developed in ethylene glycol at room temperature under ambient air conditions using 1-amino-2-propanol (AmIP) as the stabilizer. Monodispersed AmIP-Cu NPs of 3.5 ± 1.0 nm were synthesized in a high yield of ∼90%. Thus, nearly 1 g of sub-10-nm Cu NP powder was obtained using a one-step synthesis for the first time. It is proposed that metallacyclic coordination stability of a five-membered ring type between the Cu and AmIP causes the high binding force of Am IP onto the Cu surface, resulting in the superior stability of the AmIP-Cu NPs in a solution. The purified powder of AmIP-Cu NPs can be redispersed in alcohol-based solvents up to high Cu contents of 45 wt % for the preparation of Cu nanoink. The resistivity of the conductive Cu film obtained from the Cu nanoink was 30 μΩ cm after thermal heating at 150 °C for 15 min under a nitrogen flow. The long-term resistance stability of the Cu film under an air atmosphere was also demonstrated.