Dong-Hoon Kim

Bio: Dong-Hoon Kim is an academic researcher from Samsung Electro-Mechanics. The author has contributed to research in topics: Copper & Oxide. The author has an hindex of 8, co-authored 66 publications receiving 849 citations. Previous affiliations of Dong-Hoon Kim include Samsung.

Large-scale synthesis of copper nanoparticles by chemically controlled reduction for applications of inkjet-printed electronics.

Abstract: Copper nanoparticles are being given considerable attention as of late due to their interesting properties and potential applications in many areas of industry. One such exploitable use is as the major constituent of conductive inks and pastes used for printing various electronic components. In this study, copper nanoparticles were synthesized through a relatively large-scale (5 l), high-throughput (0.2 M) process. This facile method occurs through the chemical reduction of copper sulfate with sodium hypophosphite in ethylene glycol within the presence of a polymer surfactant (PVP), which was included to prevent aggregation and give dispersion stability to the resulting colloidal nanoparticles. Reaction yields were determined to be quantitative while particle dispersion yields were between 68 and 73%. The size of the copper nanoparticles could be controlled between 30 and 65 nm by varying the reaction time, reaction temperature, and relative ratio of copper sulfate to the surfactant. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) images of the particles revealed a spherical shape within the reported size regime, and x-ray analysis confirmed the formation of face-centered cubic (FCC) metallic copper. Furthermore, inkjet printing nanocopper inks prepared from the polymer-stabilized copper nanoparticles onto polyimide substrates resulted in metallic copper traces with low electrical resistivities (≥3.6 µΩ cm, or ≥2.2 times the resistivity of bulk copper) after a relatively low-temperature sintering process (200 °C for up to 60 min).

Conductive paste composition for low temperature firing

Abstract: Disclosed is a conductive paste composition for low temperature firing, including conductive copper powder composed of flake powder, spherical powder and nano powder, a melamine-based binder, and an organic solvent, thus enabling the formation of a conductive wire having a high aspect ratio with high printability, and inexpensive formation of a metal wire, and exhibiting superior electrical properties and adhesive force even when conducting low temperature firing at 200° C. or less, so that the conductive paste composition can be usefully applied as a conductive material for forming electrodes of a variety of products such as solar cells, touch panels, printed circuit boards (PCBs), radio-frequency identification (RFID), plasma display panels (PDPs) and so on.

Method for preparing metal nanoparticles using matal seed and metal nanoparticles comprising metal seed

Abstract: It provides a method for preparing metal nanoparticles using a metal seed and metal nanoparticles including the metal seed, the method including: preparing a solution by adding a polymer surfactant in an alcohol solvent; heating the solution; forming a metal seed by adding a first metal salt of at least one metal salt selected from the group consisting of platinum, palladium and iridium in the heated solution; and adding a second metal salt into the solution including the metal seed. This method allows the production of uniform-sized nanoparticles under high concentration conditions in high yield and mass production in which the metal nanoparticles have high dispersion stability so that they are suitable for various application.

Improvement of Electrical and Mechanical Properties of Ag Nanoparticulate Films by Controlling the Oxygen Pressure

Abstract: Improvement of Electrical and Mechanical Properties of Ag Nanoparticulate Films by Controlling the Oxygen Pressure Seol-Min Yi, Ji-Hoon Lee, Na-Rae Kim, Sungil Oh, Seonhee Jang, Donghoon Kim, Jaewoo Joung, and Young-Chang Joo Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, Korea Samsung Electro-Mechanics, Central R&D Institute, Suwon, KyoungGi-Do 443-743, Korea

Conductive Nanomaterials for Printed Electronics

Abstract: This is a review on recent developments in the field of conductive nanomaterials and their application in printed electronics, with particular emphasis on inkjet printing of ink formulations based on metal nanoparticles, carbon nanotubes, and graphene sheets. The review describes the basic properties of conductive nanomaterials suitable for printed electronics (metal nanoparticles, carbon nanotubes, and graphene), their stabilization in dispersions, formulations of conductive inks, and obtaining conductive patterns by using various sintering methods. Applications of conductive nanomaterials for electronic devices (transparent electrodes, metallization of solar cells, RFID antennas, TFTs, and light emitting devices) are also briefly reviewed.

Metal-based Inkjet Inks for Printed Electronics

Abstract: A review on applications of metal-based inkjet inks for printed electronics with a particular focus on inks con- taining metal nanoparticles, complexes and metallo-organic compounds. The review describes the preparation of such inks and obtaining conductive patterns by using various sintering methods: thermal, photonic, microwave, plasma, electri- cal, and chemically triggered. Various applications of metal-based inkjet inks (metallization of solar cell, RFID antennas, OLEDs, thin film transistors, electroluminescence devices) are reviewed.

Synthesis and optical properties of copper nanoparticles prepared by a chemical reduction method

Abstract: Copper nanoparticles, due to their interesting properties, low cost preparation and many potential applications in catalysis, cooling fluid or conductive inks, have attracted a lot of interest in recent years. In this study, copper nanoparticles were synthesized through the chemical reduction of copper sulfate with sodium borohydride in water without inert gas protection. In our synthesis route, ascorbic acid (natural vitamin C) was employed as a protective agent to prevent the nascent Cu nanoparticles from oxidation during the synthesis process and in storage. Polyethylene glycol (PEG) was added and worked both as a size controller and as a capping agent. Cu nanoparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy to investigate the coordination between Cu nanoparticles and PEG. Transmission electron microscopy (TEM) and UV–vis spectrometry contributed to the analysis of size and optical properties of the nanoparticles, respectively. The average crystal sizes of the particles at room temperature were less than 10 nm. It was observed that the surface plasmon resonance phenomenon can be controlled during synthesis by varying the reaction time, pH, and relative ratio of copper sulfate to the surfactant. The surface plasmon resonance peak shifts from 561 to 572 nm, while the apparent color changes from red to black, which is partly related to the change in particle size. Upon oxidation, the color of the solution changes from red to violet and ultimately a blue solution appears.

Copper Nanoparticles for Printed Electronics: Routes Towards Achieving Oxidation Stability

Abstract: In the past few years, the synthesis of Cu nanoparticles has attracted much attention because of its huge potential for replacing expensive nano silver inks utilized in conductive printing. A major problem in utilizing these copper nanoparticles is their inherent tendency to oxidize in ambient conditions. Recently, there have been several reports presenting various approaches which demonstrate that copper nanoparticles can resist oxidation under ambient conditions, if they are coated by a proper protective layer. This layer may consist of an organic polymer, alkene chains, amorphous carbon or graphenes, or inorganic materials such as silica, or an inert metal. Such coated copper nanoparticles enable achieving high conductivities by direct printing of conductive patterns. These approaches open new possibilities in printed electronics, for example by using copper based inkjet inks to form various devices such as solar cells, Radio Frequency Identification (RFID) tags, and electroluminescence devices. This paper provides a review on the synthesis of copper nanoparticles, mainly by wet chemistry routes, and their utilization in printed electronics.