• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.623-625
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• 2004

In Electro-Luminescence Display making process, it is necessary to do high molecule patterning effectively. Recently, one of the most effective way is the patterning method using Ink-Jet head controller. To maximize the effect, it is needed to control each channel of Ink-Jet head and develop that controller. Thus, we implement the Ink-Jet Head Controller which can control the parameters of 128 fire pulses independently, improve the accuracy of patterns more than 100 times previous ones, and apply random patterns.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.318-319
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• 2000

1987년에 Tang과 VanSlyke가 유기발광물질중의 하나인 8-hydroxyquinoline aluminum(Alq$_3$)을 사용하여 유기발광소자의 특성[1]을 발표하였으며, 1990년에 영국의 Cambridge대학 Cavendish 연구소는 Poly(p-phenylene vinylene)[2]를 이용한 고분자 발광소자의 특성을 보고하였다. 저분자와 고분자를 이용한 이 두 편의 논문은 낮은 인가전압, 높은 형광효율, 반도체의 성격을 보고하고 있다. 이와 같은 특성들은 실질적인 전기 발광소자에 대한 적용 가능성 및 대형 디스플레이에 대한 개발 잠재력[3]을 시사하고 있다. 특히 본 연구에 사용된 Fabry-Perot 공진기 형태의 광학적 미세공동구조는[4,5] 발광파장을 조절할 수 있을 뿐만 아니라 에너지 재분포로 인해 발광세기를 향상시킬 수 있다는 점에서 다른 EL소자들이 가지는 일반적인 구조와 대조되는 장점을 가지고 있다. (중략)

• Journal of Information Display
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• v.8 no.1
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• pp.10-13
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• 2007

We synthesized new blue and bluish green emitting materials by using fully substituted ethylene moieties. Multi-layered EL devices were fabricated with synthesized materials and evaluated in terms of emission color and luminescence efficiency. TBBPE[EML 2] device showed bluish-green CIE value of (0.236, 0.412) and 5.02cd/A at $10mA/cm^2$. BPBBPE[EML 3] device also showed sky-blue CIE value of(0.218, 0.355) and 2.31cd/A at $l0mA/cm^2$.

• Journal of Information Display
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• v.2 no.4
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• pp.8-14
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• 2001

Three types of conjugated polymers, poly(PZ-Pi), poly(PZ-BPI) and poly(PZ-NPI) were synthesized by Schiff-base reaction. These new conjugated polymers exhibited improved solubility in common organic solvents due to the presence of alkyl side chains as well as azomethine groups, Double layer LEDs made with the synthesized polymers as emitting layer and $Alq_3$, as electron transporting layer exhibited enhanced EL emission and efficiency compared to those of single layer LEDs. Double layer LEDs exhibited gradual shift in the emission peak th the single layer LED, made of only $Alq_3$ as the emitting layer as the thickness of $Alq_3$ layer increased.

• Journal of Information Display
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• v.4 no.2
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• pp.13-18
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• 2003

We synthesized bis (2-methyl-8-quinolinolato)(triphenylsiloxy) aluminum (III) (SAlq), a blue-emitting material having a high luminous efficiency, through a homogeneous-phase reaction. The photoluminescence (PL) and electroluminescence (EL) spectra of SAlq show two peaks at 454 nm and 477 nm. Efficient white light-emitting devices are fabricated by doping SAlq with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8yl) vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 results in light-emission of both blue and orange colors. Devices with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nmj/Al show EL peaks at 456 nm and 482 nm originating from SAlq and at 570 nm from DCM2, resulting in the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.37). The device exhibits an external quantum efficiency of about 2.3 % and a luminous efficiency of about 2.41m/W at 100 $cd/m^2$. A maximum luminance of about 23,800 $cd/m^2$ is obtained at the bias voltage of 15 V.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.55-60
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• 2021

In order to produce wearable displays with high adhesion while maintaining flexible characteristics, the adhesive method using electro plating method was carried out. Laser lift-off (LLO) transcription was also used to remove sapphire substrates from LEDs bonded to fibers. Afterwards, the SEM and EDS data of the sample, which conducted the adhesion method using electro plating, confirmed that copper actually grows through the lattice of the fiber fabric to secure the light source and fiber. The adhesion characteristics of copper were checked using Universal testing machine (UTM). After plating adhesion, the characteristics of the LLO transcription process completed and the LED without the transcription process were compared using probe station. The electroluminescence (EL) according to the enhanced current was measured to check the characteristics of the light source after the process. As the current increases, the temperature rises and the bandgap decreases, so it was confirmed that the spectrum shifted. In addition, the change in the electrical characteristics of the samples according to the radius change is confirmed using probe station. The radius strain also had mechanical strength that copper could withstand bending stress, so the Vf variation was measured below 6%. Based on these results, it is expected that it will be applied to batteries, catalysts, and solar cells that require flexibility as well as wearable displays, contributing to the development of wearable devices.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.667-670
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• 2007

A new series of highly bright and efficient poly(pphenylenevinylene) s (PPV)s based on polyhedral oligomeric silsesquioxanes (POSSs) was synthesized via the Gilch polymerization method. The three POSScontaining PPVs are as follows: POSS05- PPV(containing 5 mol % POSS-appended PPV units), POSS25-PPV(containing 25 mol % POSS-appended PPV units), and POSS100-PPV(containing 100 mol % POSS-appended PPV units; this is the first ${\pi}-conjugated$ polymer composed of 100 mol % POSSsappended repeating units). The POSS-containing PPVs exhibit higher glass transition temperatures $(64-77^{\circ}C)$ than that of MEH-PPV $(58^{\circ}C)$, indicating that electroluminescence (EL) devices fabricated with these polymers should have good thermal stabilities. Light-emitting diodes (LEDs) with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated using the novel POSS-containing PPVs. Surprisingly, the luminescence efficiency (0.48 cd/A at $10540\;cd/m^2$) of the binary blend consisting 5 wt % of POSS25-PPV and 95 wt % of MEH-PPV was found to be enhanced by a factor of 6.4 with a maximum brightness of $11010cd/m^2$ (at 14.3 V).

• Journal of Information Display
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• v.3 no.2
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• pp.1-5
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• 2002

A CMOS driving circuit for active matrix type polymer electroluminescent displays was designed to develop an on-chip microdisplay on the single crystal silicon wafer substrate. The driving circuit is a conventional structure that is composed of the row, column and pixel driving parts. 256 gray scales were implemented using pulse amplitude modulation method. The 2-transistor driving scheme was adopted for the pixel driving part. The layout was carried out considering the compatibility with the standard CMOS process. Judging from the layout of the driving circuit, it turns that it is possible to implement a high-resolution display about 400 ppi resolution. Through the HSPICE simulation, it was verified that this circuit is capable of driving a VGA signal mode display and implementing 256 gray levels.

• 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.

• Journal of Information Display
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• v.3 no.1
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• pp.6-10
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• 2002

We have synthesized a new green Ir(III) complex fac-tris-(3-methyl-2-phenyl pyridine)iridium(III) $Ir(mpp)_3$ and fabricated phosphorescent polymer light-emitting device using it as a triplet emissive dopant in PVK. $Ir(mpp)_3$ showed absorption centered at 388 nm corresponding to the $^1MLCT$ transition as .evidenced by its extinction coefficient of the order of $10^3{\cdot}$ From the PL and EL spectra of the $Ir(mpp)_3$ doped PVK film, the emission maximum was observed at 523 nm, due to the radiative decay from the $^3MLCT$ state to the ground state, confirming a complete energy transfer from PVK to $Ir(mpp)_3$. The methyl substitution has probably caused a red shift in the absorption and emission spectrum compared to $Ir(mpp)_3$. The device consisting of a 2 % doped PVK furnished 4.5 % external quantum efficiency at 72 $cd/m^2$ (current density of 0.45 $mA/cm^2$ and drive voltage of 13.9 V) and a peak luminance of 25,000 $cd/m^2$ at 23.4 V (494 $mA/cm^2$). This work demonstrates the impact of the presence of a methyl substituent at the 3-position of the pyridyl ring of 2-phenylpyridine on the photophysical and electroluminescence properties.