• 조명전기설비학회논문지
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• 제23권12호
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• pp.23-30
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• 2009

LED조명장치는 자동차분야, 항공, 디스플레이, 전송장치 그리고 특수조명등의 응용장치로의 활용이 증가하고 있다. 일반적으로 고출력 RGB 멀티칩 LED는 표시용이나 경관조명용 또는 감성조명용으로 적용되고 백색 LED는 표시용 조명에서 최근 들어 일반조명용으로 적용되고 있으며, 고출력 백색 LED의 출시와 광효율의 증가는 이를 더욱 가속화하고 있다. 본 논문에서는 백색 LED와 RGB 멀티칩 LED 조명장치를 동일한 사양으로 제작하여 물리적, 전기적, 광학적 조명특성을 분석하여 향후 LED조명시스템의 제작에 정량적 데이터를 제공하고자 한다. 이를 위해 LED의 주요한 물리적 특성인 방열특성에 대한 성능분석, 전기적 특성의 분석을 위한 전력 및 드라이브 효율에 대한 성능분석을 수행하였고 조명특성을 위한 연색성, 배광특성, 광효율을 측정하였다. 백색 LED와 RGB 멀티칩 LED 조명장치를 활용한 응용장치의 적용방법을 확립하고 나아가 다양한 조명시스템에 LED 조명장치를 적용하는데 참고가 되는 기초 데이터를 제시하고자 한다.

• 한국전기전자재료학회논문지
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• 제16권9호
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• pp.816-825
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• 2003

Current-voltage-luminance characteristics of organic light-emitting diodes (OLEDs) were measured in the temperature range of 10 K～300 K. Indium-tin-oxide (ITO) was used as an anode and aluminum as a cathode in the device. Organic of N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) was used for a hole transporting material, and tris (8-hydroxyquinolinato) aluminum (Alq$_3$) for an electron transporting material and emissive material. And copper phthalocyanine (CuPc), poly(3,4-ethylenedi oxythiophene);poly(styrenesulfonate) (PEDOT:PSS), and poly(N-vinylcarbazole) (PVK) were used for hole-injection buffer layers. From tile analysis of electroluminescence (EL) and photoluminesccnce (PL) spectra of the Alq$_3$, the EL spectrum is more greenish then that of PL. And the temperature-dependent current-voltage characteristics were analyzed in the double and multilayer structure of OLEDS. Electrical conduction mechanism was explained in the region of high-electric and low-electric field. Temperature-dependent luminous efficiency and operating voltage were analyzed from the current-voltage- luminance characteristics of the OLEDS.

• Journal of Information Display
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• 제2권4호
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• pp.29-33
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• 2001

The luminance and discharge characteristics of an AC PDP may be significantly affected by a small amount of impurity gas in working gas. Impurity gases such as $O_2$, O , C and $H_2$ can be mixed in the manufacturing and lor discharge processes. In this paper, a small amount of impurity gas in AC PDP are introduced intertimally and the relationship between the amount of impurity gas and the luminance/discharge characteristics are investigated. The luminous efficiency decreased seriously with the increase in the partial pressure of impurity gases, especially in $H_2$, $O_2$ and $CO_2$, Under the condition of the impurity gas ratio of 2x $10^{-3}$ for Ar, $N_2$, $H_2$, $CO_2$ and $O_2$, the luminous efficiency decreased to about 8%, 8%, 32%, 36% and 50%, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.147-147
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• 2015

The multilayer structure of the organic light emitting diode has merits of improving interfacial characteristics and helping carriers inject into emission layer and transport easier. There are many reports to control hole injection from anode electrode by using transition metal oxide as an anode buffer layer, such as V2O5, MoO3, NiO, and Fe3O4. In this study, we apply thin films of LiF which is usually inserted as a thin buffer layer between electron transport layer(ETL) and cathode, as an anode buffer layer to reduce the hole injection barrier height from ITO. The thickness of LiF as an anode buffer layer is tested from 0 nm to 1.0 nm. As shown in the figure 1 and 2, the luminous efficiency versus current density is improved by LiF anode buffer layer, and the threshold voltage is reduced when LiF buffer layer is increased up to 0.6 nm then the device does not work when LiF thickness is close to 1.0 nm As a result, we can confirm that the thin layer of LiF, about 0.6 nm, as an anode buffer reduces the hole injection barrier height from ITO, and this results the improved luminous efficiency. This study shows that LiF can be used as an anode buffer layer for improved hole injection as well as cathode buffer layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.174-177
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• 2001

We have seen the effects of buffer layer in organic light-emitting diodes using poly(N-vinylcarbazole)(PVK). Polymer PVK buffer layer was made using spin casting techniques. Two different types of spin casting have been applied; static coating and dynamic coating. Two device structures were fabricated; one is ITO/TPD/Alq$_3$/Al as a reference, and the other is ITO/PVK/TPD/Alq$_3$/Al to see the effects of buffer layer in organic light-emitting diodes. Current-voltage characteristics and luminous efficiency were measured with a variation of spin-casting methods and rpm speeds. We have obtained an improvement of luminous efficiency by a factor of two and half when the PVK buffer layer is used.

• 전기학회논문지
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• 제58권1호
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• pp.155-159
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• 2009

To increase the luminance and luminous efficacy in the discharge for alternating current plasma display panel (ac PDP), the increment of Xe contents and long discharge gap are necessary. However, the driving voltage and the cost of driving circuit increases in the high Xe contents and long discharge path condition. In this paper, a long gap ITO hump electrode (LGH) model for discharge cells of ac PDP is evaluated in the various Xe contents($5{\sim}20%$). The discharge voltage of LGH structure is lower about 30V than that of ITa reference structure with same main discharge gap. The LGH structure has lower power consumption and higher luminance than those of reference structure, respectively. Also, the luminous efficacy of LGH structure is higher about 20% than that of ITO reference structure in the 20% Xe contents.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권2호
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• pp.37-41
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• 2001

In this study, organic electroluminescent devices with the ITO/TPD/Alq$_3$/cathode structure, using various materials of Al, Mg:Ag, Al:Li, MgF$_2$/Al, and LiF/Al as cathodes, were fabricated. We investigated the electrical and optical properties of the devices as follow: current density-voltage(J-V), luminance-voltage(L-V) and luminous efficiency-voltage curves. The bilayer cathodes with LiF/Al and MgF$_2$/Al exhibited better device performance than the other cathodes. It is considered that the improved performance of the organic electroluminescent devices is attributable to the lowering of driving voltage caused by the enhanced electron injection. The alkaline-earth fluorides are desirable materials to improve the performance of the EL devices with the Al cathode, and high luminous efficiency was achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1815-1817
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• 2000

Plasma display Panels(PDPs) are one of the leading technologies currently under development for large-area high-brightness flat panel displays. However, the luminance and luminous efficiency of at PDPs should be improved. Especially, one of the main factors affecting on the luminance and luminous efficiency of ac PDP may be the phosphor thickness and size of discharge space. In this study, we examined into addressing time, electrical and optical properties as a parameter of the phosphor thickness and the size of discharge space during the display period of ac PDP. It is found out that the optimum phosphor thickness was $50{\mu}m$ and height of discharge space was about $100{\mu}m$.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권9호
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• pp.436-442
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• 2002

Recently color AC PDP(plasma display panel) technology is rapidly improved. However, the luminous efficiency improvement is a key issue for making plasma display into a large-area flat display. In this paper, we suggest a new concentration of Xe in He-Ne-Xe gas mixture in order to achieve a high luminous efficiency of color AC PDPs. We calculated the densities of 25 species as a function of the time zero dimensional simulation using CVODE solver and we compared the results of zero dimensional simulation with a measurement of photo wave brightness and luminous efficiency, in order to find the optimum mixing condition of He-Ne-Xe gas in color plasma display panel. We obtained a high discharge speed under Xe mixing ratio of 1% by simulation and confirmed that through measuring photo wave.

• 한국조명전기설비학회지:조명전기설비
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• 제10권4호
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• pp.53-61
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• 1996

광원에 대하여 서로 다른 여러 각도방향에서 광원을 바라볼 때 관측되는 광도 분포 및 재귀반사성능을 측정하기 위해 광도 분포 측정장치(배광측정기)를 제작하였다. 이 장치는 광원을 좌우로 360도, 상하로 $\pm$30도 회전 시킬수 있는 광원회전장치, 광검출기로 광전자증배관(PM Tube)을 쓰는 수광부 및 재귀반사성능 측정용 투광기와 제어 및 표시부로 구성되어 있다. 광도측정범위는 0.01~199900cd, 관측각범위는 0.2~1.5도 이고 광도의 측정오차는 $\pm$3%이다. 제작된 장치의 구조와 성능평가결과가 제기되었다.