• Journal of Information Display
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• 제7권2호
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• pp.26-30
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• 2006

Insertion of a thin lithium fluoride (TLF) layer between an emitting layer (EML) and an electron transporting layer has resumed in the developement of a highly efficient and bright organic light-emitting diode (OLED). Comparing with the performance of the device as a function of position with the TLF layer in tris-(8-hydroxyquinoline) aluminum $(Alq_{3})$, we propose the optimal position for the TLF layer in the stacked structure. The fabricated OLED shows a luminance efficiency of more than 20 cd/A, a power efficiency of 12 Im/W (at 20 mA/$cm^{2}$), and a luminance of more than 22 000 cd/$m^{2}$ (at 100 mA/$cm^{2}$), respectively. We suggest that the enhanced performance of the OLED is probably attributed to the improvement of carrier balance to achieve a high level of recombination efficiency in an EML.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1511-1514
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• 2009

Organic light emitting layer in OLED device was formed by gravure printing process in this work. Organic surface coated by gravure printing typically showed relatively bad uniformity. Thickness and roughness control was characterized by applying various mixed solvents in this work. Poly (N-vinyl carbazole) (PVK) and fact-tris(2-phenylpyridine)iridium($Ir(ppy)_3$) are host dopant system materials. PVK was used as a host and Ir(ppy)3 as green-emitting dopant. To luminance efficiency of the plasma treatment on etched ITO glass and then PEDOT:PSS spin coated. The device layer structure of OLED devices is as follow Glass/ITO/PEDOT:PSS/PVK+Ir(ppy)3-Active layer /LiF/Al. It was printed by gravure printing technology for polymer light emitting diode (PLED). To control the thickness multi-printing technique was applied. As the number of the printing was increased the thickness enhancement was increased. To control the roughness of organic layer film, thermal annealing process was applied. The annealing temperature was varied from room temperature, $40^{\circ}C$, $80^{\circ}C$, to $120^{\circ}C$.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2008년도 추계학술발표대회 및 제15회 신소재 심포지엄
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• pp.11.2-11.2
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• 2008

• 한국광과학회:학술대회논문집
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• 한국광과학회 2001년도 학술대회지
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• pp.23-23
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• 2001

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.234-234
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• 2006

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.340-343
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• 2002

We report here our recent progress in the development and commercialization of polyfluorenes emitting red, green and blue (ROB) colors as materials for light emitting diodes (LEDs). Our patented version of the Suzuki coupling process has been used to synthesize a variety of fluorenebased homopolymers and copolymers emitting colors across the entire visible spectrum. The optical and electronic properties of the polymers are tailored through selective incorporation of different aromatic units into the polyfluorene backbone. Our latest green emitter, reported herein, provides very efficient devices with a low turn-on voltage of 2.25 V, a peak efficiency of 10.5 Cd/A at 6,600 Cd/$m^2$ at 4.85 V. These devices maintain an efficiency of greater than 10 Cd/A up to 50,000 Cd/$m^2$ and demonstrate very good stability as exemplified by a device half-life of greater than 1,500 hours starting from 1,100 Cd/$m^2$. Considerable progress has also been made with red and blue emitters and will be the subject of this presentation.

• ETRI Journal
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• 제45권6호
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• pp.1056-1064
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• 2023

The optical properties of the materials composing organic light-emitting diodes (OLEDs) are considered when designing the optical structure of OLEDs. Optical design is related to the optical properties, such as the efficiency, emission spectra, and color coordinates of OLED devices because of the microcavity effect in top-emitting OLEDs. In this study, the properties of top-emitting blue OLEDs were optimized by adjusting the thicknesses of the thin metal layer and capping layer (CPL). Deep blue emission was achieved in an OLED structure with a second cavity length, even when the transmittance of the thin metal layer was high. The thin metal film thickness ranges applicable to OLEDs with a second microcavity structure are wide. Instead, the thickness of the thin metal layer determines the optimized thickness of the CPL for high efficiency. A thinner metal layer means that higher efficiency can be obtained in OLED devices with a second microcavity structure. In addition, OLEDs with a thinner metal layer showed less color change as a function of the viewing angle.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1779-1783
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• 2006

The hybrid thin-film (HTF) passivation layer composed of the UV curable acrylate layer and MS-31 (MgO:SiO2=3:1wt%) layer was adopted in organic light emitting diode (OLED) to protect organic light emitting materials from penetrations of oxygen and water vapors. The moisture resistance of the deposited HTF layer was measured by the water vapor transmission rate (WVTR). The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007g/m^2$ per day at $37.8^{\circ}C$ and 100% RH. Therefore, the HTF on the OLED was found to be very effective in protect what from the penetrations of oxygen and moisture.

• KSBB Journal
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• 제28권3호
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• pp.170-176
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• 2013

The purpose of this study was to determine optimum condition of Pavlova lutheri and Phaeodactylum tricornutum. Detailed studies were carried out on the effects of various wavelengths of light-emitting diodes (LEDs), light intensities and air flow rations. For the Pa. lutheri, cell growth rates and maximum cell concentrations were similar regardless of wavelengths and air flow rates. Among the different light intensities, cell concentration increased when light intensity of red LED increased. For Ph. tricornutum, red LED was found to be the most effective light source, and light intensity of 3,100 Lux resulted in the most effective for the cultivation of Ph. tricornutum. Different air flow rates were tested to overcome shading effects due to denser cell concentration in the solution. Aeration of 0.8 vvm was determined to be the optimum aeration rate for the cultivation of Ph. tricornutum. Especially, five and two times greater cell concentrations of Pa. lutheri and Ph. tricornutum, respectively, were observed when air was applied.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.127-128
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• 2000

Organic light-emitting diodes(OLEDs) are constructed using multilayer organic thin films. The hole-transport layer is PVK and the emitting material is rubrene and $Alq_3$. The emitting layer is doped with rubrene partially. As the partially-doped layer migrate from the interface PVK/emitting layer, the emission peak of rubrene decrease and diminish. By comparing with the previous reports, we propose the zero-field hole injection barrier at ITO/PVK interface and hole-trapping effect of rubrene in host materials as predominant factor to determine the emission zone.