• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.903-906
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• 2003

Doping a small amount of a phosphorescent dye into an organic light-emitting diodes(OLED) can lead to a significant improvement in the device properties. The fluorescent host materials like TAZ, CBP have been used, but have a problem of rapid decay of efficiency at high current densities. To alleviate this problem, phosphorescent host was introduced. The whole configuration of OELD fabricated was ITO/a-NPD(50nm)/Zn $cluster:Ir(ppy)_{3}(30nm)/BCP{(10nm)/Alq_{3}(20nm)$ /Al:Li. The OLED showed high luminance (> 50,000 $cd/m^{2}$ ) and external efficiency(5.7%). At higher current densities, rapid decay of external quantum efficiency or host emission, which was frequently observed in the fluorescent host system, were not observed.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.37-40
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• 2002

We have been fabricated the white organic electroluminescent devices using vacuum evaporation method. The structure of the white OELD is Glass/1T0/NPB/DPVBi/AI $q_{3:}$ Ru bren e/B CP/Alq $q_3$/Al. We have got the white emission with two-wavelength that is mixing blue emission in DPVBi layer and orange emission in Al $q_{3:}$Rubrene layer by varying tile doping concentrations of Rubrene and the thickness of NPB layer.yer.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.167-170
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• 2002

We have proposed new pixel structures for Active Matrix OELD (AMOELD) to improve the uniformity of luminance and manufactured a full-color 3.6-inch QVGA AMOELD. The proposed pixel structures, composed of four TFTs and one capacitor, can display 64 gray scales by compensating threshold voltage (Vth) variation of driving TFTs. Nonuniformity and peak intensity of measured luminance are under 14% and over $200cd/m^2$, respectively.

• Korean Journal of Materials Research
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• v.13 no.8
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• pp.514-518
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• 2003

As a fundamental study on organic electroluminescence(EL), blue emitting materials were synthesized and characterized. Individual blue colored hydrazone derivatives were synthesized from the reaction of aldehydes (phthalaldehyde, isophthalaldehyde) with the corresponding amnios (1-methyl -1-phenylhydrazine, 1,1-diphenylhydrazine hydrochloride). Recrystallization of hydrazones from chloroform revealed the melting temperature within $142∼156^{\circ}C$. Photoluminescence(PL) analysis on each hydrazone showed that emission range were blue(458∼478 nm). The structure of obtained hydrazones were elucidated by FT-IR, $^1$H-NMR and C, H, N elemental analyzer.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.9-13
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• 2002

Recently, Organic electroluminescent devices (OELDs) have been demonstrated the medium sized full color display with effective multi-layer thin films. In this study, the multi-layer OELDs were prepared on the patterened ITO (indium tin oxide)/glass substrates by the vacuum thermal evaporation method. The low molecule compounds such as $Alq_3$(trim-(8-hydroxyquinoline)aluminum) and CTM (carrier transfer material) as the electron transport and injection layers as well as TPD (triphenyl-diamine) and CuPc (copper phthalocyanine) as the hole transport and injection layers were used. The luminance was rapidly increased above the threshold voltage of 10 V. The luminance and emission spectrum for the OELDs samples with $A1/CTM/Alq_3$/TPD/1TO structures were found to be 430 cd/$m^2$and 512 nm at 17 V showing green color emission. In contrast, the samples with $Li-A1/Alq_3$/TPD/CuPC/1TO multi-structures showed 508 nm in emission spectrum and 650 cd/$m^2$at 17 V in the luminance. The increment of luminance may be ascribed to the improved efficiency of recombination in the region of the emission layers by the deposition of CuPc as hole injection layer and the low work function of the Li-Al electrode compared to the Al electrode.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.168-168
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• 2012

Al doped ZnO (AZO)는 태양전지, 평판 디스플레이, OELD 등 광전자 소자에 적용되는 투명전도막용 재료인 ITO의 대체 재료로서 최근에 가장 각광받고 있는 물질이다. 하지만, $2.5{\times}10^{-4}{\Omega}{\cdot}cm$의 낮은 비저항과 90% 이상의 투과도를 갖는 ITO의 비해 AZO의 특성은 아직 부족한 상황이다. 수십 년간 많은 연구자들에 의해 다양한 제조 방법과 공정 조건들로 전기적, 광학적 특성을 향상시키기 위한 노력들이 진행되어 왔다. 하지만 실리콘 반도체와는 달리 II-VI족 물질의 정확한 근본적인 원리는 아직 불분명한 상태이다. 지금까지 AZO의 특성 향상의 원인을 결정립 크기, 주상구조의 우선 방위, 결정성, Zn-O 구조내의 산소 결핍 등의 메커니즘으로 설명해 왔다. 하지만, 본 연구에서는 지금까지 제안된 상기 요인의 변화 없이 전기적, 광학적 특성을 향상시키는 것이 짧은 열처리만으로도 가능했다. AZO 박막의 전기적, 광학적 특성에 큰 영향을 미치는 보다 근본적인 원인은 도핑 효율이다. ZnO 내에 도핑된 Al의 양보다 실제로로 활성화된 Al의 비율을 올리는 것이 중요하다. 본 연구에서 구조적, 조성적 변화 없이 도핑효율을 8.9%에서 66.7%까지 증가시켰으며, 이동도는 박막 표면의 및 결정립계 사이의 과잉산소를 줄임으로서 optical phonon scattering 감소를 통하여 증가시킬 수 있고, 이러한 과잉산소의 감소는 deep level emission을 감소시킴으로서 투과도 증가에도 영향을 준다. 본 연구에서 짧은 열처리를 통해 구조적 변화 없이 도핑효율의 증가만으로 $4.8{\times}10^{-4}{\Omega}{\cdot}cm$의 비저항과 90%의 투과도를 갖는 AZO 박막을 제조하였다.

• Journal of the Korean Applied Science and Technology
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• v.17 no.1
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• pp.63-66
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• 2000

Organic Electroluminescent devices(OELD) consisted of multilayer structures have been studied for the application the application to flat-panel display. Metal-chelate complexes, zinc bis(2-(2-hydroxyphenyl)benzoxazolate) ($Zn(BOX)_{2}$) and zinc bis(2-(2-hydroxyphenyl)benzothiazolate) ($Zn(BOX)_{2}$), have been intensively investigated as an white-light emitting layer and recognized to have good electroluminescent(EL) properties. In this study, ($Zn(BOX)_{2}$) and ($Zn(BTZ)_{2}$) were synthesized and characterized by FT-IR, $^{1}H-NMR$, UV-VIS and PL. Their EL properties were also studied and their ionization potential(IP) and electron affinity(EA) were also measured by cyclic voltammetry(CV).

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.11-14
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• 2003

A silicon based OELD driving circuit that has a new type of column driving method is proposed to reduce the driving circuit area. In comparison with the conventional method, latches in each column are removed and one DAC (digital-to-analog converter) drives several column lines. To make the DAC operate during a specific period for the low power consumption, a simple DESG (DAC Enable Signal Generator) circuit was devised and confirmed by the simulation.

• Transactions on Electrical and Electronic Materials
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• v.3 no.2
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• pp.16-19
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• 2002

In this study, a novel red emitting organic electroluminescent (EL) device was fabricated with the bis(8-oxyquinolino)zinc II (Znq2) doped dye as an emitting layer. The Znq2 was synthesized successfully from zinc chloride (ZnC1$_2$) as an initial material. Then, we fabricated the red organic EL device with a dye (DCJTB) doped and inserted Znq2 between emission layer and cathode for increasing EL efficiency. The hole transporting layer is a N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-1,1'-diphenyl-4,4-diamine (TPD), and the host material of emission layer is Znq2. And the electrical and luminance characteristics of the device were measured. We found that the EL device with Znq2 inserting layer results in the increasing luminance efficiency.

• 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.