• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.39-44
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• 2022

The light extraction technology for improving the light efficiency of OLEDs is the core technology for extracting the light inside the OLEDs to the outside. This study demonstrates a simple method to generate random nanostructures (RNSs) containing high refractive index nanoparticles to improve light extraction and viewing angle characteristics. A simple dry low-temperature process makes the nanostructured scattering layer on the polymer resin widely used in the industry. The scattering layer has the shape of randomly distributed nanorods. To control optical properties, we focused on changing the shape and density of RNSs and adjusting the concentration of high refractive index nanoparticles. As a result, the film of the present invention exhibits a perpendicular transmittance of 85% at a wavelength of 550 nm. This film was used as a scattering layer to reduce substrate mode loss and improve EL efficiency in OLEDs.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.389-396
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• 2010

In this paper, we reported the synthesis and electroluminescent properties of blue fluorescent styrylamine derivatives end-capped with a diphenylvinyl group. A new series of styrylamine derivatives have been synthesized via the Horner-Wadsworth-Emmons reaction. To explore electroluminescent properties of these molecules, multilayer organic lighte-mitting devices with the configuration of ITO/NPB/1-5 doped in MADN/Bphen/Liq/Al were fabricated. All devices exhibited blue emissions with good EL performances. Among those reported herein, the device using dopant 5 exhibited a maximum luminance of $24,000\;cd/m^2$ at 11.0 V, a luminous efficiency of 12.5 cd/A at $20\;mA/cm^2$, a power efficiency of 6.50 lm/W at $20\;mA/cm^2$, and $CIE_{x,y}$ coordinates of (x = 0.173, y = 0.306) at 8.0 V, all of which demonstrate the superiority of these materials in blue OLEDs.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1549-1552
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• 2006

We report a new series of blue dopants composed of both electron donating and electron accepting moieties in one molecule, based on nalidixic acid. The EL device derived from the dopant exhibits pure blue light emission (0.15, 0.14) The current efficiency is estimated to be 3.88 cd/A at 100 $cd/m^2$, which shows remarkable enhancement, compared to that of the host itself (2.5 cd/A at 100 $cd/m^2$) under the same conditions. These results demonstrate that the incorporation of a proper guest into the host in a guest-host doped system improves not only the purity of the fluorescent blue emission but also elevates its quantum efficiency, thus improving the OLED performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.939-942
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• 2001

We fabricated Red Organic light-emitting devices(OLED). The Basic Device Structure is ITO/hole transfer layer, TPD(50nm)/red emitting layer, Alq3 doped with DCM2 or DCM2:rubrene(xnm)/electorn transfer layer, Alq3(50-xnm)/LiF(0.8nm)/Al(8nm) . The thickness of emitting layer(xnm) changed 5, 10, 20nm. we demonstrate red emitting OLED with dependent on the thickness and concentrators of Alq3 layer doped with DCM2 or co-doped with DCM2:ruberene. The Emission color and Brightness are changed with doping or co-doping condition, dopant concentarton. In the case of rubrene:DCM2 co-doped layer structure, the red color Purity and device efficiency is improved. The CIE index of rubrene co-doped OLED is x=0.67, y=0.31. By co-doping the Alq3 layer with DCM2, rubrene, EL efficiency improved from 0.38cd/A to 0.44cd/A in comparison whit DCM2 doped Alq3 layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.940-943
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• 2003

We report the fabrication and the characterization of white organic light-emitting devices consisting of a red-emitting layer of a new DCM derivative doped into 4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (${\alpha}-NPD$) and a blue-emitting layer of 1,4-bis(2,2-diphenyl vinyl)benzene (DPVBi). The device structure is ITO/PEDOT:PSS/${\alpha}-NPD$ (50 nm)/${\alpha}-NPD$:DCM (5 nm, 0.2 %)/DPVBi (x)/Alq3 (40 nm)/LiF (0.5 nm)/Al. The electroluminescence (EL) spectra consist of two broad peaks around 470 nm and 580 nm with the spectral emission depending on the thickness of DPVBi. The device with the DPVBi thickness of about 20 nm show a white light-emission with the Commission Internationale d'Eclairage(CIE) chromaticity coordinates of (0.33, 0.36). The external quantum efficiency is 2.6% and luminous efficiency is 2.0 lm/W at a luminance of 100 $cd/m^{2}$. The maximum luminance is about 30,270 $cd/m^{2}$ at 13.9 V.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1466-1468
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• 2001

For the full color organic electro-luminescent device, essentially, red, green, and blue emissions are required. But red emission is not to reach minimum level of practical use 31[lm/W]. In order to optimize color purity and power consumption requirements, it is important for the materials development efforts to search for improvements in red emission effisiency. In this study, the bis(8-oxyquinolino)zinc II ($Znq_2$) were synthesized successfully from zinc chloride($ZnCl_2$) as a initial material. Then, we fabricated red organic electroluminescent device with a dye(DCJTB)-doped and inserted $Znq_2$ between emission layer and cathode layer for increasing EL efficiency. The hole transfer layer is a N,N'-diphenyl-N,N'-bis-(3-methyl phenyl) -1,1'-diphenyl-4.4'-diamine(TPD), and the host material of emission layer is $Znq_2$. For the inserting of $Znq_2$, efficiency increased.

• Journal of Information Display
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• v.8 no.2
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• pp.15-19
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• 2007

We have studied the effect of host materials on the electrophosphorescence properties by comparing three different host materials such as tris(8-hydroxyquinoline)-aluminum (III) $(Alq_3)$, bis(8-hydroxyquinoline)-zinc (II) $(Znq_2)$, and 4,4'-N,N' dicarbazole-biphenyl (CBP) doped with a red-emissive phosphorescent dye, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (PtOEP). The EL spectra show a strong red emission (peak at 650 nm) from the triplet excited state of PtOEP and a very weak emission from an electron transport layer of $Alq_3$ and a hole transport layer of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1-biphenyl-4,4'-diamine (TPD). We find that the triplet exciton lifetime and the quantum efficiency decrease in the order of CBP, $Alq_3$, and $Znq_2$ host materials. The results are interpreted as a poor exciton confinement in $Alq_3$, and $Znq_2$ host compared with in CBP. Therefore, it is very important for the triplet-exciton confinement in the emissive layer for obtaining a high efficiency.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2139-2144
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• 2008

There are eight kinds of railroad vehicles such as KTX, PP(Push-Pull), NEL(New Electric Locomotive), EL(Electric Locomotive), DL(Diesel Locomotive), CDC(Commuter's Diesel Car), VVVF(Variable Voltage Variable Frequency) and Resistance Control Car that Korail corporation presently runs, and a variety of vehicles just like EMU(Electric Multiple Unit) and DMU(Diesel Multiple Unit) currently developed and accepted are running in the near future. However, There is still no design standard of the control stand of cockpit and the same compatibility of forms and control unit arrangements for locomotive engineers because no one has tried to approach in an ergonomic way. It can cause Locomotive engineers to make errors using the machinery. when the new vehicles are adopted, The efficiency of operation will quite fall down due to the separate training of the engineers. Therefore, We'd like to improve the accuracy of manipulating the machinery used by the engineers at all times according to the design standard of ergonomic technology and safety engineering and increase the operational efficiency and the safety of railroad vehicles in order to handle the problems as quickly as we can in an emergent situation.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.1014-1018
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• 2007

We have demonstrated the enhancement of the power efficiency and device lifetime of organic light-emitting diodes (OLEDs) by introducing the ETL 1 / ETL2 (composite ETL) structure between EML and cathode and the HIL1 (composite HIL) / HIL2 between anode and HTL. Compared to reference devices retaining conventional architecture, novel OLED structure shows an outstanding EL efficiency that is 1.6 times higher (${\sim}4.5$ lm/w versus ${\sim}$ 2.71 lm/w for the reference device) and lower driving voltage $({\bigtriangleup}V>1V)$, but also a longer lifetime and smaller operating voltage drift over time. It is suggested in this work that the device performance can be improved by in-situ ohmic contact through novel electron controlled structure and reduction of charge accumulation in the interface through composite HIL

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.86-91
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• 2011

Modified lignins were prepared. Soda and peroxy lignins were precipitated from black liquor produced from bagasse pulping with soda and peroxyacid pulping process. The precipitated lignins were hydrolyzed using 10% HCl. Different functional groups were also incorporated into lignin by carboxylation and phosphorylation reactions. Moreover crosslinking of these lignins were carried out using epichlorohydrin. Characterization of the modified lignins and lignins derivative were carried out using Infrared spectroscopy. Thermal analysis of these compounds were also carried out using TGA and DTA techniques. Efficiency of sorption of metal ions by the modified lignin was also investigated. It was found that, the peroxylignin and its derivatives show higher efficiency toward metal ions uptake than the soda lignin.