Young-Cho Kim

Highly Oriented Gold/Nanoclay–Polymer Nanocomposites for Flexible Gas Barrier Films

Layer-by-layer (LBL) assembly, which uses electronic and ionic intermolecular bonding under nonvacuum conditions, is a promising technology for fabricating gas barrier films owing to its simple processing and easy formation of a multilayer structure. In this research, nanoclay-polymer multilayers of Na(+)-montmorillonite (Na-MMT) were fabricated. Particularly, the addition of AuCl3 on fabricated MMT layers caused a reaction with the surface silanol functional groups (Si-O-H) of the MMT platelets, resulting in the formation of Au2O3 on the MMT-polymer multilayers. The Au2O3 filled the vacancies between the MMT platelets and linked the MMT platelets together, thus forming a gas barrier film that reduced the water vapor transmission rate (WVTR) to 3.2 × 10(-3) g m(-2) day(-1). AuCl3-treated MMT-polymer multilayers thus have the potential to be utilized for manufacturing gas barrier films for flexible electronics on a large scale.

Improvement of Electric and Optical Properties of a Reflective Electronic Display by Particle-Moving Method

We propose a new particle-insertion method for a reflective display based on the structure of a quick response-liquid powder display (QR-LPD). To compare this method with the reported simple loading method, two panels are fabricated in the same panel condition of which the width of ribs is 30 μm, the cell size is 220 μm 220 μm, the cell gap is 116-120 μm, the m value of the black particles is μC/g and that for the white particles is μC/g. This method excludes the non-moving particles, inserting only mobile particles into a substrate by using electric fields so that a panel fabricated by the particle-moving method can drive most of the particles in a cell. Also, most of the particles move at the threshold voltage of 40 V with enhanced reflectivity.

Color Realization of Reflective Electronic Display Using Particle-Moving Method

We propose a color realization method of a reflective display based on quick response-liquid powder display (QR-LPD). We use the particle-moving method in order to address the color particles cyan, magenta, yellow, and black (CMYK) into their respective cells. We fabricated a color addressed reflective display panel using indium-tin-oxide (ITO) glass with a rib width of 15 μm, a cell size of 300 μm × 300 μm, an average particle diameter of 8 μm, and a particle charge to mass ratio (q/m) from +8.5 μC/g to -4 μC/g. Most particles are inserted into their cells on the upper substrate, with non-movable particles removed in a previous step. The fabricated color panel shows a well-addressed CMYK array in microscopic photographs. An additional color display is fabricated using line-by-line addressing in order to facilitate the addressing process.

Stability of Particle Movement in Reflective Electronic Displays by Analysis of the Response Time

In this study, we propose a measurement system for extracting the response time of negatively and positively charged particles having contrasting colors. The system consists of a laser, a photodiode, a shield box, a power supply, and an oscilloscope. The response times measured by this system are used to analyze the movement of oppositely charged particles, to determine the appropriate driving waveform, and to the filtering voltage of the particle-moving method. The particle-moving method controls the response times and the electrical balance of oppositely charged particles in a panel.

Analysis of Particle Movement by Dielectrophoretic Force for Reflective Electronic Display

We analyze the movement of particles in an electric paper that consists of upper and lower electrodes. Particles inserted in a fluid move under the influence of an electric field when voltage is applied to the electrodes. The movement of particles is determined by the intensity of the electric field, the viscosity of the fluid, and the q/m of the particles. Each factor has an impact on the independent particles. Considering these factors, we analyze the characteristics of the particles movements. We analyze the behavior of the electric paper with experiments based on Stokes Law.

A Study on Driving Characteristics by Particle-inserting Method in Charged Particle Type Display

We analyzed the movement and response time of charged particles according to particle-inserting methods to understand the variation of quantity of q/m of charged particles, which is a very important factor in electrical and optical characteristics of the charged particle type display, such as lifetime, response time, contrast ratio, reflectivity, etc. For our study we used white and black charged particles of which diameter is , prepared pieces of ITO(indium tin oxide) coated glass substrate, and formed ribs on the glass substrates. The width of a rib is and the cell size is . As the particle-inserting methods, the white and black charged particles were respectively inserted into a front and a rear panel with a very small electric field and also the mixture of the white and black charged particles were inserted into a rear panel. As a result of the driving characteristics of charged particles, the factors about variation of quantity of q/m according to the particle inserting method was experimentally demonstrate, showing very different driving voltage, response time, the particle movement, etc.

Fabrication and Addressing Method of Charged Particle Type Display

The charged particle type display is a kind of electronic paper showing information images using positive and negative charged particles (

Studies on Analysis of Particle Lumping and Improvement of Driving Characteristics in Charged Particle Type Display

The authors investigated the field emission characteristics of printed carbon nanotubes (CNTs) on KOVAR substrates with micro- and nanosize line patterns. Microsized line patterns were fabricated using photolithography techniques followed by an inductive coupled plasma-reactive ion etching process, and laser interference lithography techniques were used to fabricate uniform nanosized patterns over a relatively large area. CNTs were printed on the patterned substrate using a screen printing method. The field emission characteristics of each patterned substrate were compared to those of a nonpatterned substrate. Results revealed that varying the pattern size has an influence on the field emission characteristics. The reduction of the pattern size results in an increase in the total surface area. This surface patterning is found to provide additional areas for CNTs to adhere to the substrates, which, in turn, results in better adhesion of CNTs. As the size of the pattern is reduced, the field emission proper...

Analysis of Driving Characteristics and Memory Effect by Occupation Area Evaluation Method of Charged Particle Type Display Device

We analyzed various forces affective to the charged particles in closed space, to explain the image degradation and lifetime-shortening phenomena because of particle lumping which is one of the serious problems in reflective displays. It is possible to predict the quantity of q/m which is the most important parameter in determining the optical and electrical characteristics, by calculating the image force and kinetic energy. For stable driving, the quantity of q/m must be in the defined range but it changes during the fabrication process, so we added the filtering process to solve this problem and obtained the well-defined nonlinear driving voltage coinciding with the threshold voltage. And we obtained the fully-driving property which prevents the particle lumping and decides the image quality and lifetime of panel from the optical characteristics and occupation surface of moving particles.