Yong-wan Jin

18.4: A New Seamless Foldable OLED Display Composed of Multi Display Panels

A new seamless foldable OLED display composed of multi display panels is proposed. To verify seamless viewing and robust folding-unfolding reliability, a 138 ppi resolution, 5.4″ diagonal size AM-OLED seamless foldable display prototype is fabricated.

Fabrication of field emission triode using carbon nanotubes

Abstract We have fabricated the triode for field emission display on soda-lime glass using carbon nanotube as an emission tip. Selective growth of carbon nanotubes was carried out on the emitter hole with the size of 1.2 μm in diameter using plasma enhanced hot filament chemical vapor deposition (HFPECVD). The emission characteristics of the fabricated triode showed that turn on electric field was 7 V/μm in diode mode and that on–off control of the emission current was achieved by gate voltage of 1 V. The emission current increased from 3 to 28.5 μA as the gate voltage increased from 0 to 2 V at the anode voltage of 1900 V.

Effect of Catalytic Layer Thickness on Growth and Field Emission Characteristics of Carbon Nanotubes Synthesized at Low Temperatures Using Thermal Chemical Vapor Deposition

The direct synthesis of carbon nanotubes (CNTs) on substrates by chemical vapor deposition (CVD) is a highly promising route for their application to field emission displays. Several stringent requirements have to be met for this purpose, including low-temperature growth below 600°C to utilize glass substrates and large-area deposition for practical use. In this study, we carried out the synthesis of CNTs by thermal CVD on glass substrates at temperatures as low as 500–550°C. CNTs were grown by thermal decomposition of CO and H2 gases at atmospheric pressure for different thicknesses of Invar (Fe–Ni–Co alloy) catalytic layers. The CNT growth was strongly correlated with the preparation conditions of the catalytic layers. The diameters and heights of as-grown CNTs increased with the catalytic layer thickness from 2 nm to 30 nm. Measurements of the field emission properties of the CNTs showed that the threshold electric fields decreased with increasing thickness of the catalytic layers. Uniform electron emission was observed over a large area of 150×150 mm2 with high emission current and high brightness.

Organic Photodiode with High Infrared Light Sensitivity Based on Tin Phthalocyanine/C60 Bulk Heterojunction and Optical Interference Effect

We demonstrated an organic near-infrared (NIR) photodiode on the basis of the bulk heterojunction (BHJ) structure by using tin phthalocyanine (SnPc) and C60 fullerene with a high incident photon–electron conversion efficiency (IPCE) of 50% at a wavelength of 750 nm. The cell showed optical responses to about 1000 nm and had a specific detectivity D* of 1.59 ×1011 cm Hz1/2/W. The SnPc:C60 ratio in the BHJ layer influenced the optical response. Higher ratios enhanced NIR sensitivity but reduced the peak IPCE; the optimal ratio was 3:1. The optical interference of directly incident light and light reflected from an Al electrode was also examined to enhance the IPCE at longer wavelengths. With a 90-nm-thick C60 layer, the first antinode of the standing wave at a wavelength of 750 nm was located at the BHJ layer; this layer enhanced the IPCE at 700 and 800 nm but reduced it at 400 nm.

Field emission from carbon nanotube emitters fabricated by the metal intermediation layer

Multiwalled carbon nanotube (MWNT) emitters fabricated by the metal intermediation process were studied. This was intended to allow strong adhesion and high electrical contact between the cathode electrode and MWNT emitters. The process was performed by hot-pressed bonding of a metal layer to a MWNT film surface, where the metal layer was deposited on a main substrate. Through this process, MWNTs have open and sharp ends, and the metal layer and the MWNTs have strong electrical contact. Together with unchanged crystallinity of MWNTs as before the process, these effects improve the field emission properties, resulting in 64% reduction of turn on field and two to three orders of magnitude increase of current density.

Stability enhancement of an electrically tunable colloidal photonic crystal using modified electrodes with a large electrochemical potential window

The color tuning behavior and switching stability of an electrically tunable colloidal photonic crystal system were studied with particular focus on the electrochemical aspects. Photonic color tuning of the colloidal arrays composed of monodisperse particles dispersed in water was achieved using external electric field through lattice constant manipulation. However, the number of effective color tuning cycle was limited due to generation of unwanted ions by electrolysis of the water medium during electrical switching. By introducing larger electrochemical potential window electrodes, such as conductive diamond-like carbon or boron-doped diamond, the switching stability was appreciably enhanced through reducing the number of ions generated.

Studies of full color field emission display core technologies with the electrical and structural analysis

Electron beam spreading and its relationship with layout of field emission display (FED) is simulated and discussed. The morphological optimization of microtips is introduced for the effect of field enhancement with the process condition. The structural effect of thin film step coverage which is formed during the fabrication of field emitter arrays (FEAs) is uniquely studied with the reliability of FED. The surface condition of phosphor and its relationship with the brightness enhancement are analyzed and studied with the specific aging step. A unique approach of gas aging for the image stabilization is introduced and fully analyzed.

Flat Panel Display Using Carbon Nanotube

We fabricated 15 inch diagonal field emission display with a double-gated structure in which the carbon nanotube was used as electron emission sources. The resolution, operation voltage, brightness, and color gamut were almost reached the values of the user demand. The lifetime and pixel-to-pixel uniformity are remained to be improved. The backlight unit of LCD was also demonstrated with carbon nanotube field emission flat lamp. The cost competition and the enhanced power efficiency are challenges to be overcome for the mass production.

Carbon‐nanotubes grown from spin‐coated nanoparticles for field‐emission displays

Abstract The density controlled carbon nanotubes (CNTs) are grown on the iron acetate nanoparticles by using the freeze‐dry method. The iron‐acetate [Fe(||)(CH3COO)2] solution is used to prepare the catalytic iron nanoparticles. The density of CNTs is controlled in order to enhance the field emission process. Furthermore, the patterning of the iron nanoparticle catalyst‐layer for the fabrication of electronic devices is simply achieved by using alkaline solution, TMAH (tetramethylammonium hydroxide). We applied this patterning process of catalyst layer to form the electron emitter with under‐gate type triode structure.