title: Expeditious low-temperature sintering of copper nanoparticles with thin defective carbon shells.
abstract: The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ∼23 nm, shell thickness ∼1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation. Isothermal oxidation and reduction treatment at 200 °C for only about 10 min yields an oxide-free copper network structure with an electrical resistivity of 25.1 μΩ cm (14.0 μΩ cm at 250 °C). Finally, conductive copper line patterns are achieved down to a 50 μm width with an excellent printing resolution (standard deviation ∼4.0%) onto a polyimide substrate using screen printing of the optimized inks.
authors: Nuclear Materials Development Division, Korea Atomic Energy Research Institute, Daeduk-daero, Dukjin-dong, Yuseong-gu, Daejeon 305-353, Republic of Korea. leeminku@kaeri.re.kr leegj@kaeri.re.kr.
authors: Changkyu
authors: C
authors: Kim
authors: Gyoungja
authors: G
authors: Lee
authors: Changkyu
authors: C
authors: Rhee
authors: Minku
authors: M
authors: Lee