Chan-Jae Lee

Erratum: “Influences of Various Metal Elements on Field Aided Lateral Crystallization of Amorphous Silicon Films”

In this study, the effects of various metals on field aided lateral crystallization (FALC) behaviors of amorphous silicon (a-Si) were investigated. Under the influence of the electric field, some metals such as Cu, Ni and Co were found to induce the lateral crystallization toward the metal-free region while Au, Al and Cr were not able to induce the crystallization of a-Si. On the other hand, the effect of the electric field on the lateral crystallization was not obvious for Pd. These phenomenological differences could be interpreted in terms of the dominant diffusing species (DDS) in the reaction between the metal and Si. It is judged that the applied electric field can enhance the crystallization velocity by accelerating the diffusion of metal atoms because the occurrence of lateral crystallization is known to rely on the diffusion of metal atoms than that of Si atoms. Therefore, it is thought that the only metal-dominant diffusing species in the reaction between metal and Si can strongly result in the crystallization of a-Si in metal-free region.

The Influence of Cu and Au on Field Aided Lateral Crystallization of Amorphous Silicon Films

The effect of Cu and Au on field aided lateral crystallization (FALC) process of amorphous silicon films was investigated. Although both Cu and Au induced the crystallization of a-Si in contact with those metals, only Cu was able to induce the lateral crystallization toward a metal-free region. Especially, the crystallization caused by Cu atoms was noticeably accelerated at the edge near the negative electrode side in every pattern under the electric field, while the lateral crystallization was retarded at the positive electrode side. The crystallization velocity increased with the applied field intensity and the annealing temperature, but it decreased with the size of test pattern. However, electric field did not affect the crystallization by Au. The maximum crystallization velocity using Cu was 770 µm/h at 500°C in the electric field of 4 V/cm and the lateral crystallization was achieved at a temperature as low as 450°C.

Crack-induced Ag nanowire networks for transparent, stretchable, and highly sensitive strain sensors

Crack-based strain sensor systems have been known for its high sensitivity, but suffer from the small fracture strain of the thin metal films employed in the sensor which results in its negligible stretchability. Herein, we fabricated a transparent (>90% at 550 nm wavelength), stretchable (up to 100%), and sensitive (gauge factor (GF) of 30 at 100% strain) strain gauge by depositing an encapsulated crack-induced Ag nanowire (AgNW) network on a hydroxylated poly(dimethylsiloxane) (PDMS) film. Stretching the encapsulated AgNWs/PDMS resulted in the formation of a percolation network of nanowire ligaments with abundant percolation paths. The encapsulating polymer was designed to adhere strongly to both the AgNW and PDMS. The improved adhesion ensured the resistance of the crack-induced network of AgNWs varied reversibly, stably, and sensitively when stretched and released, at strains of up to 100%. The developed sensor successfully detected human motions when applied to the skin.

Driving characteristics of poly(N-vinylcarbazole) and 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3-4-oxadiazole-based polymer light emitting diodes

We studied the driving characteristics of Poly(N-vinylcarbazole) (PVK)-based polymer light emitting diodes (PLEDs) by incorporating various 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3-4-oxadiazole (PBD) concentrations. PVK (Mn=25,000∼50,000 g/mol) and tris(2-(4-tolyl)phenylpyridine)iridium (Ir(mppy)3) were used as the host and dopant materials, respectively. The transient electroluminescence (EL) of the PLED measurement was used to analyze the characteristics of the carrier transport by synchronizing the DC-pulse generator (10 V, 70 Hz) and photodiode. Among the fabricated PLEDs including those with different PBD concentrations from 0% to 60%, the devices with 60% PBD concentration showed the highest efficiency (15.5 cd/A) at 1000 cd/m2. By increasing the PBD concentration, a shorter rising time of the PLEDs was achieved possibly due to improved transport behavior of the electrons by the PBD incorporation. This result is well agreement with the increased device efficiency by increasing the PBD concentration, which shows that the transient EL measurement can be a good method for analyzing PLED performance and charge balancing.

P‐82: Top Emission Organic Light Emitting Diode with Ni Anode

The hole injection and emissive properties of top emission organic light emitting diodes with Nickel anode were investigated. The effect of oxygen plasma treatment on the Ni anodes was also investigated for enhancing the electrical properties of the devices. The device with Ni anode having an high work function shows better hole injection and emission characteristics than that with ITO. Oxygen plasma treatment of Ni anode induced further improvement of electrical properties and surface toughness. CIE coordinates of top emission device were different from bottom emission device. Ni anode induced the internal quantum efficiency of the device to be improved.

Flexible metal–insulator–metal (MIM) devices for plastic film AM-LCD

Abstract We developed new flexible metal–insulator–metal (MIM) devices subject to plastic film substrate. The structure of the MIM device is that a Ta2O5 insulator is covered with two flexible Al electrodes on both sides. The flexible structure of the MIM device was successfully fabricated applying our own etch-free process.

29.2: Top Emission Organic EL Display on Paper Substrate

We introduce top emission organic light emitting devices (TEOLEDs) on paper substrate. The Substrate selected was a commercial ink-jet paper. Paper was coated with a polymer to prevent water penetration and out gassing and to improve surface roughness. We studied substrate properties as a function of coating structure and material on paper and fabricated device. It consisted of a metal anode having with work function and a semi-transparent cathode. It shows brightness over 400cd/m2 and working well on the rolled state.

Hybrid Passivation for a Film-like Organic Light-Emitting Diode using Parylene and Silicon Dioxide

A hybrid passivation method a using parylene and silicon dioxide combination layer for a film-like organic light-emitting diode (OLED) was applied on a polycarbonate substrate. Parylene coating by vapor polymerization is a highly effective passivation process for the OLED, and it is applied to the entire top surface and the edges of the OLED device. To minimize the permeation of moisture and oxygen from the top surface of the device, an additional layer of silicon dioxide was deposited over the parylene-coated layer. It was found that the water vapor transmittance rate (WVTR) of parylene (15 µm in thickness)/SiO2 (0.3 µm in thickness) combination layers deposited on the polycarbonate film was decreased to less than 10-3 g/(m2d). The OLED that had undergone hybrid passivation showed significantly longer lifetime characteristics in ambient conditions than the non-passivated OLED. The lifetime of the passivated OLED was 400 h and it was more than ten times the lifetime of the conventional non-passivated OLED.

Top Emission Organic Light Emitting Diode with Transparent Cathode, Ba-Ag Double Layer

Abstract We fabricated top emission organic light emitting diode (TEOLED) with transparent metal cathode Barium and Silver bilayer. Very thin Ba/Ag bilayer was deposited on the organic layer by thermal evaporation. This cathode showed high transmittance over 70% in visible range, and the device with a Ba‐Ag has a low turn on voltage and good electrical properties.

Effect of Ag Capping Layer on the Emission Characteristics of Transparent Organic Light-emitting Devices with Ca/Ag Double-layer Cathodes

We have investigated the effects of an Ag capping layer on the emission characteristics of transparent organic light-emitting devices with Ca/Ag double-layer cathodes. The thickness of the Ag layer was varied from 10 to 30 nm, whereas the Ca was fixed to be a 10 nm in the Ca/Ag structure. The luminance and current efficiency on the cathode and anode sides are significantly dependent on the Ag thickness. For example, the current efficiency on the anode side increases from 8.4 to 11.7 cd/A, whereas, on the cathode side, it decreases from 3.2 to 0.2 cd/A as the Ag thickness increases from 10 to 30 nm. These changes in emission characteristics were investigated by measuring electroluminescence, transmission, and reflection spectra.