Dae-Woo Ihm

Highly Transparent Tin Oxide Films Prepared by DC Magnetron Sputtering and Its Liquid Crystal Display Application

A thin film of tin oxide (SnO2) was prepared on a plastic substrate by DC magnetron roll sputtering. The deposition thickness of SnO2 rapidly decreased with the increase of O2 gas flow rate, even though the refractive index remained almost constant at the level of 2.0 after the flow rate exceeded 40 sccm. The SnO2 thin film was applied as the oxide layer of the inner side of the multilayer conductive electrode having the sandwich structure of the oxide/metal/oxide system for flat panel display (FPD). The SnO2 layer in the sandwich structure (SnO2/Ag/ In2O3–SnO2; ITO) serves as a nucleation modification layer of the metal layer while preventing the diffusion of materials from the metal layer (Ag) to the barrier layer (SiO2). In particular, the transmittance in the 600–700 nm range is about 10% higher than that measured for the ITO/Ag/ITO structured electrode. This multilayered conductor also has approximately 5–8 Ω/square electrical resistance and 85% optical transmission at 550 nm.

Polymer-dispersed liquid crystal devices using highly conducting polymers as electrodes

Flexible all-organic polymer-dispersed liquid crystal (PDLC) devices were fabricated by using highly transparent and conductive poly(3,4-ethylenedioxy thiophene): p-toluene sulfonate (PEDOT:PTS) films, as electrode layers. These conductive PEDOT:PTS films have a high transparency up to 80%, and possess a very low sheet resistance of 100Ωsq−1 at 100nm thickness. We report on the fabrication and characterization of a PDLC device using a highly conductive PEDOT:PTS for the electrodes and demonstrate its superior performance relative to that of a similar device using the indium tin oxide layer as the electrodes.

Transparent multi-layer conductive electrode film prepared by DC sputter deposition and its flat panel display application

Multi-layer conductive electrode films to be used as a substrate for a plastic liquid crystal display (LCD) were prepared by the DC magnetron roll-to-roll sputtering method. The conductive layer is consisted of three layers, ITO/Ag/ITO, ITO/APC/ITO and SnO 2 /Ag/ITO, on the polymer substrate. The multi-layered conductive electrode has sheet resistance of about 5-8 Ω/square, optical transparency of 85-88 % at 550 nm, and appropriate gas permeability. In particular, the ITO/APC/ITO structured electrode shows about 5-10 % higher transmittance at 600-800 nm ranges than structures of SnO2/Ag/ITO and ITO/Ag/ITO.

Preparation and Characterization of Conductive Polymer Nano-Films

We investigate the electrically conductive polypyrrole(PPy)and poly(3,4-ethylenedioxythiophene, PEDOT)nano-films prepared in a continuous roll-to-roll process by vapor-phase polymerization method. Thin films of ferric chloride doped conductive PPy and PEDOT on plastic substrates, in which neither matrix polymers nor binders are used for the film forming process, are obtained at nano-level thickness. PPy and PEDOT film thickness was varying depend on reaction time and reaction temperature. The surface resistance change with time of exposure to monomer vapors, and the value was in the range of 103 ∼ 105 Ω/sq. at 20–60 nm thick films and showed up to 600Ω/sq. for the > 600 nm thick films. These thin films had a very highly ordered surface morphology. Especially, in the case of PEDOT film, the growth of highly ordered conductive PEDOT crystalline microstructure, which high anisotropy, parallel to the substrate film was fabricated, was observed by AFM.

P‐78: Process Simplification for Passive Matrix OLEDs

We have developed simplified processes for the formation of insulators, cathode separators and bus electrodes in PMOLEDs. The insulators and cathode separators are patterned simultaneously by a single layer of image reversal photoresist. And, the bus electrodes of low resistance are formed by the cathode separator and cathode metal. Using these simplified processes, we fabricated 1.17″ 96×RGB×96 panels and analyzed their performance and reliability.

Anisotropic conductive film (ACF) prepared from epoxy/rubber resins and its fabrication and reliability for LCD

Abstract A thermoset type anisotropic conductive adhesive film (ACAF) comprising epoxy resin and natural butyl rubber (NBR) as the binder, micro‐encapsulated imidazole as the curing agent, and Ni/Au coated polymer bead as a conductive particle has been studied. These films have been prepared to respond to requirements such as improved contact resistance, current status less of than 60 μm and reliability. These films can also be used for connection between the ITO glass for LCD panel and the flexible circuit board. The curing conditions for the connection were 40, 20 and 15 seconds at 150, 170 and 190 °C, respectively. The initial contact resistance and adhesion strength were 0.5 O/square and 0.4 kg/cm under the condition of 30 kgf/cm2, respectively. After completing one thousand thermal shock cycling tests between ‐15 °C and 100 °C, the contact resistance was maintained below 0.7 O/square. Durability against high temperature (80 °C) and high humidity (85 % RH) was also tested to confirm long‐term stability (1000 hrs) of the conduction.