• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.779-780
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• 2009

New inverted architecture of a hybrid inorganic-organic light-emitting diode, utilizing ZrO2 electron-injecting layer, is presented. The thickness of the ZrO2, as well as the annealing of the light-emitting polymer, is found critical to obtain good performance. A range of light-emitting polymers is shown to operate efficiently in the proposed architecture.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1219-1221
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• 2008

The Authors have demonstrated highly efficient white organic light-emitting diodes using hybrid-spacer which was inserted between each emitting layer or/and codoped blue emitting layers with the different functional material. The characteristics of WOLEDs showed the maximum external quantum efficiency of 13.8%, power efficiency of 33.66 lm/W, and Commission Internationale de I'Eclairage coordinates of (x=0.36, y=0.37), respectively.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.208-211
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• 2009

The authors have demonstrated the various characteristics of hybrid white organic light-emitting diodes (HWOLED) using fluorescent blue and phosphorescent red emitters. We also demonstrated that two devices showed different characteristics in accordance with thickness of the 4,4′-N,N′-dicarbazole-biphenyl (CBP) spacer (CS) inserted between the blue and the red emitting layer. It was found that the device with a CS thickness of 70 $\AA$ showed a current efficiency 2.5 times higher than that of the control device with a CS thickness of 30 $\AA$ by preventing the triplet Dexter energy transfer from the red to the blue emitting layer. The HWOLED with the CS thickness of 70 $\AA$ exhibited a maximum luminance of 24500 cd/$m^2$, a maximum current efficiency of 42.9 cd/A, a power efficiency of 37.5 lm/W, and Commission Internationale de I'Eclairage coordinates of (0.37, 0.42).

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.588-590
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• 2008

Yellow-emitting $Y_3Al_5O_{12}$:Ce nanocrystalline phosphor and orange-emitting CdS:Mn/ZnS core/shell quantum dots were prepared by a modified polyol and a reverse micelle chemistry, respectively. To compensate a poor color rendering index of YAG:Ce nanocrystalline phosphor due to the lack of red spectral component, CdS:Mn/ZnS quantum dots were blended into YAG:Ce. Based on spectral evolutions in the blended systems, hybrid white light emitting diodes are fabricated and characterized.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.418-420
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• 2009

The Authors have demonstrated high efficiency hybrid white organic light-emitting diodes (HWOLED) for reduced efficiency roll-off and color stability. It was shown that HWOLED fabricated in this study have the maximum luminance of 46 420 cd/$m^2$ at 8 V (turn-on voltage of 2.7 V), external quantum efficiency of 13.18%, power efficiency of 28.75 lm/W at 1 000 cd/$m^2$, and reduced efficiency roll-off of 2.7 times than control white device. The HWOLED also showed the stable color shift with $\Delta$Commission Internationale de I'Eclairage coordinates coordinates of ${\pm}$ (0.00, 0.00) from 100 to 10000 cd/$m^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.47-47
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• 2011

There have been numerous efforts to enhance the efficiency of light-emitting diodes (LEDs) by using low dimensional structures such as quantum dots (QDs), wire (QWRs), and wells (QWs). We demonstrate QD/QWR/QW hybrid structured LEDs by using nano-scaled pyramid structures of GaN with ~260 nm height. Photoluminescence (PL) showed three multi-peak spectra centered at around 535 nm, 600 nm, 665 nm for QWs, QWRs, and QDs, respectively. The QD emission survived at room temperature due to carrier localization, whereas the QW emission diminished from 10 K to 300 K. We confirmed that hybrid LEDs had zero-, one-, and two-dimensional behavior from a temperature-dependent time-resolved PL study. The radiative lifetime of the QDs was nearly constant over the temperature, while that of the QWs increased with increasing temperature, due to low dimensional behavior. Cathodoluminescence revealed spatial distributions of InGaN QDs, QWRs, and QWs on the vertices, edges, and sidewalls, respectively. We investigated the blue-shifted electroluminescence with increasing current due to the band-filling effect. The hybrid LEDs provided broad-band spectra with high internal quantum efficiency, and color-tunability for visible light-emitting sources.

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.238-243
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• 2022

In this study, a pyrene-core single molecule with amino (-NH₂) functional group material was hybridized using ZnO quantum dots (QDs). The suppressed performance of the 1-aminopyrene (1-PyNH₂) single molecule as an emissive layer (EML) in light-emitting diodes (LEDs) was exploited by adopting the ZnO@1-PyNH₂ core-shell structure. Unlike pristine 1-PyNH₂ molecules, the ZnO@1-PyNH₂ hybrid QDs formed energy proximity levels that enabled charge transfer. This result can be interpreted as an improvement in surface roughness. The uniform and homogeneous EML alleviates dark-spot degradation. Moreover, LEDs with the ITO/PEDOT:PSS/TFB/EML/TPBi/LiF/Al configuration were fabricated to evaluate the performance of two emissive materials, where pristine-1-PyNH₂ molecules and ZnO@1-PyNH₂ QDs were used as the EML materials to verify the improvement in electrical characteristics. The ZnO@1-PyNH₂ LEDs exhibited blue luminescence at 443 nm (FWHM = 49 nm), with a turn-on voltage of 4 V, maximum luminance of 1500 cd/m², maximum luminous efficiency of 0.66 cd/A, and power efficiency of 0.41 lm/W.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.996-998
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• 2004

In this study, we tested parylene as the passivation layer for flexible organic light emitting diodes (FOLEDs).Parylene as passivtion layer has several advantages which are good optical transparent and low moisture penetration. For more an effective passivation of FOLEDs, we suggest hybrid passivation layer with parylene and silicon oxide. We compared electrical properties and stability of the device with and without passivation layer. The lifetime of FOLED with hybrid passivation layer was increased over three times than that of non-passivated of FOLED.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.374-374
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• 2012

Nowadays, Active Matrix Organic Light-Emitting Diodes (AM-OLEDs) are the superior display device due to their vivid full color, perfect video capability, light weight, low driving power, and potential flexibility. One of the advantages of AM-OLED over Liquid Crystal Display (LCD) lies in its flexibility. The potential flexibility of AM-OLED is not fully explored due to its sensitivity to moisture and oxygen which are readily present in atmosphere, and there are no flexible encapsulation layers available to protect these. Therefore, we come up with a new concept of Inorganic-Organic hybrid thin film as the encapsulation layer. Our Inorganic layer is Al2O3 and Organic layer is F-Alucone. We deposited these layers in vacuum state using Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) techniques. We found the results are comparable to commercial requirement of 10-6 g/m2 day for Water Vapor Transmission Rate (WVTR). Using ALD and MLD, we can control the exact thin film thickness and fabricate more dense films than chemical or physical vapor deposition methods. Moreover, this hybrid encapsulation layer potentially has both the flexibility of organic layers and superior protection properties of inorganic layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.581-586
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• 2015

We studied optical and electrical properties of two-wavelength white tandem organic light-emitting diodes using red and blue materials. White fluorescent OLEDs were fabricated using Alq3 : Rubrene (3 vol.% 5 nm) / SH-1 : BD-2 (3 vol.% 25 nm) as emitting layer (EML). White single fluorescent OLED showed maximum current efficiency of 9.7 cd/A, and tandem fluorescent OLED showed 18.2 cd/A. Commission Internationale de l'Eclairage (CIE) coordinates of single and tandem fluorescent OLEDs was (0.385, 0.435), (0.442, 0.473) at $1,000cd/m^2$, respectively. White hybrid OLEDs were fabricated using SH-1 : BD-2 (3 vol.% 10 nm) / CBP : $Ir(mphmq)_2(acac)$ (2 vol.% 20 nm) as EML. White single hybrid OLED showed maximum current efficiency of 7.8 cd/A, and tandem hybrid OLED showed 26.4 cd/A. Maximum current efficiency of tandem hybrid OLED was more twice as high as single OLED. CIE coordinates of single hybrid OLED was (0.315, 0.333), and tandem hybrid OLED was (0.448, 0.363) at $1,000cd/m^2$. CIE coordinates in white tandem OLEDs compared to those for single OLEDs observed red shift. This work reveals that stacked white OLED showed current efficiency improvement and red shifted emission than single OLED.