• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.486-489
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• 2018

Solution-processed organic light-emitting diodes (OLEDs) have the advantages of low cost, fast fabrication, and large-area devices. However, most studies on solution-processed OLEDs have mainly focused on solution-processable hole transporting materials or emissive materials. Here, we report fully solution-processed green OLEDs including hole/electron transport layers and emissive layers. The electrical and optical properties of OLEDs based on solution-processed TPBi (2,2',2"-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) as the electron transport layer were investigated with respect to the spin speed and the number of layers. The performance of OLEDs with solution-processed TPBi exhibits a power efficiency of 9.4 lm/W. We believe that the solution-processed electron transport layers can contribute to the development of efficient fully solution-processed multilayered OLEDs.

• Fashion & Textile Research Journal
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• v.8 no.1
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• pp.129-133
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• 2006

To develope a high value-added fiber products which is useful in the human body physiology, the Macban stone was deposited on the PET fabric by sputtering and its effects were investigated. Then, a Macban stone target was prepared for sputtering treatment and treated on the PET fabric by RF sputtering process. After treatment, surface observation by SEM, far-infrared emissivity and emissive power, the fastness to washing and light, bacteriostatic rate, electrostatic, drape stiffness, and breaking strength of PET fabric were investigated. From these investigation, the following conclusions were obtained. 1) The Macban stone was able to deposit on the PET fabric, by the RF sputtering treatment which is eco-friendly dry textile finishing. 2) The far-infrared emissivity and emissive power of sputtered PET fabrics were increased. 3) When PET fabric was treated by sputtering with Macban stone, the amount of deposited Macban stone increased with increasing treatment time and it was deposited on the fabric surface firmly. 4) The bacteriostatic rate of sputtered PET fabrics was about 20%. 5) The electrostatic charge of fiber surface was reduced by sputtering. 6) The fastness washing to light of dyed fabric were improved by the deposition of Macban stone, but the breaking strength was not changed by sputtering. 7) The drape stiffness of sputtered PET fabrics increased with increasing treatment time.

• Transactions on Electrical and Electronic Materials
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• v.8 no.5
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• pp.218-221
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• 2007

High-efficiency white organic light-emitting diodes(WOLEDs) were fabricated with two emissive layers and an blocking layer was sandwiched between two phosphorescent dopants, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III(FIrpic) as the blue emission and a newly synthesized red phosphorescent material guest, bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate($(acppy)_2Ir(acac)$). This blocking layer prevented a T-T annihilation in a red emissive layer, and balanced with blue and red emission as blocking of hole carriers. The white device showed Commission Internationale d'Eclairage($CIE_{x,y}$) coordinates of (0.317, 0.425) at 22400 $cd/m^2$, a maximum luminance of 27300 $cd/m^2$ at 268 $mA/cm^2$, a maximum luminous efficiency and power efficiency of 26.9 cd/A and 18.6 lm/W.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1136-1146
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• 2005

In this paper, the radiative electric field intensity due to the communication signal and conductive noise is calculated in overhead medium voltage power lines for power line communication. The input impedance is calculated by means of 2 port equivalent model of medium voltage power line network and basic transmission line theory. And then, currents is calculated by calculated input impedance and finally, the emissive electric field is calculated. The input impedance appears like a standing wave form with a fixed cycle because high reflection at the input terminal due to the characteristic impedance of medium voltage power line is very large. A calculated current and radiative electric field also appears like this form. From the measurement results, the measured results are very similar to the calculated results.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1116-1119
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• 2008

We developed phosphorescent white OLEDs with high efficiency and color stability. By engineering device architecture in which confined excitons within the emissive layer by using adequate interlayer and balanced recombination of charge carriers by using stepwise hole transporting layer system, these WOLEDs showed power efficacy of 43.6 lm/W with CRI = 62 and 36 lm/W with CRI = 72 at $100\;cd/m^2$ without outcoupling enhancements.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.402-405
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• 2002

본 연구에서는 22.9KV 중전압 삼상 배전선로에 9KHz-30MHz의 주파수를 반송파신호로 인가하였을 때 나타나는 방사전계를 측정하였다. 중 전압 통신채널을 대지귀로방식으로 디지털신호를 인가하였을 때 3m와 10m법의 표준 방사전계 측정법을 적용하였다. 삼삼 배전선로에서 단일신호 보다 다중 신호전송에서 방사전력이 우수함이 나타내었으며 다중전송신호의 세기를 20㏈m로 하였을 때 1.8km까지 전송가능함을 확인하였고, 반송주파수 30MHz에 대하여 10m 측정법으로 방사전계를 측정하였더니 40㏈u/m임을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.30-33
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• 2008

Using a $Ir(ppy)_3$ doped in hole and electron transport host materials, simple three layers green PHOLEDs comprising double emissive layers have been fabricated. A low driving voltage value of 3.3 V to reach a luminance of $1000\;cd/m^2$ and maximum current- and power-efficiency values of 53.9 cd/A and 57.8 lm/W are demonstrated in this simple structure phosphorescent OLED.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.135-138
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• 2006

OLEDs are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEDs in the ITO(indium-tin-oxide)/N,N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• ETRI Journal
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• v.31 no.6
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• pp.642-646
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• 2009

Highly efficient white phosphorescent organic light-emitting diodes with a mixed-host structure are developed and the device characteristics are studied. The introduction of a hole-transport-type host (N, N'-dicarbazolyl-3-3-benzen (mCP)) into an electron-transport-type host (m-bis-(triphenylsilyl)benzene (UGH3)) as a mixed-host emissive layer effectively achieves higher current density and lower driving voltage. The peak external quantum and power efficiency with the mixed-host structure improve up to 18.9% and 40.9 lm/W, respectively. Moreover, this mixed-host structure device shows over 30% enhanced performance compared with a single-host structure device at a luminance of 10,000 $cd/m^2$ without any change in the electroluminescence spectra.