• 한국전기전자재료학회논문지
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• 제33권3호
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• pp.194-200
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• 2020

Perylene bisimide derivatives are developed for red organic phosphor because of their advantages, such as excellent luminous efficiency and high thermal stability. Despite these advantages, they have poor solubility characteristics in organic solvents and short emission wavelength as red organic phosphor for hybrid light-emitting diodes (LEDs). In this study, we prepared terrylene bisimide using a coupling reaction and swallow-tail imide group, which has excellent solubility. The structures and properties of swallow-tail terrylene bisimide (9C) were analyzed using ¹H-nuclear magnetic resonance (¹H-NMR), Fourier-transform infrared (FT-IR), UV/Vis spectroscopy, and thermal gravimetric analysis (TGA). The maximum absorption wavelength of (9C) in the UV/Vis spectrum was 647 nm, and the maximum emission wavelength was 676 nm. In the TGA, (9C) demonstrated good thermal stability with less than 5 wt% weight loss up to 415℃. In the solubility test, (9C) has a good solubility of more than 5 wt% in chloroform and dichloromethane. When the compounds (9C) were mixed with PMMA (polymethly methacrylate), the films showed peaks at 680 nm in the PL spectra. The results verify the suitability of (9C) as a red organic phosphor for hybrid LEDs.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.594-599
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• 2011

분무열분해 공정을 이용하여 $SrAl_2O_4:Eu$ 녹색 형광체를 제조함에 있어 붕소의 치환, 유기첨가제 및 건조 조절제의 사용에 따른 발광 특성을 조사하였다. Al 자리에 붕소를 치환시켜 줌으로써 결정상은 순수해지고 발광강도는 크게 향상됨을 확인하였다. 휘도 측면에서 붕소의 함량은 약 1 at%로 하는 것이 가장 바람직하였다. 유기첨가제의 함량 변화에 따른 $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ 형광체의 휘도 변화를 조사한 결과 0.2M을 사용했을 때 가장 높은 휘도를 얻었다. 유기첨가제와 함께 건조 조절제로 DMF 0.5M을 함께 사용함으로써 $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ 형광체의 휘도는 약 172% 향상되었다. XRD 분석 결과에 의하면 사용한 유기첨가제와 DMF의 사용은 $Sr_{0.9}Al_{1.98}B_{0.02}O_4:Eu_{0.1}$ 형광체의 결정상 변화 없이 결정성을 크게 향상시켰다. 유기 첨가제만을 사용할 경우 형광체의 표면적은 커졌지만 DMF를 함께 사용함으로써 현저히 줄어들었다. 따라서 유기첨가제와 DMF를 동시에 사용하여 합성한 형광체의 휘도가 크게 향상된 것은 결정성 증가와 표면적 감소에 기인한 것이라고 결론지었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.791-794
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• 2003

To synthesize $Gd_{2}O_{3}:Eu$ phosphor powder of nano size and high luminescence efficiency under UV (ultraviolet) and VUV (vacuum ultraviolet) light, organic additives such as citric acid and ethylene glycol and $Na_{2}CO_{3}$ flux were introduced in large-scale spray pyrolysis and critical conditions for forming nano-sized particles were investigated. The $Gd_{2}O_{3}:Eu$ phosphor particles prepared from solutions with organic additives such as citric acid and ethylene glycol had micron size and spherical shape. However, the particles prepared from polymeric precursor solution with $Na_{2}CO_{3}$ flux had nano size and non-aggregation characteristics. The as-prepared spherical particles with micron size turned into nano-sized particles during post-treatment by recrystallization process. The nano-sized $Gd_{2}O_{3}:Eu$ phosphor particles showed higher brightness than the commercial $Y_2O_3:Eu$ phosphor product under both UV light of 254nm and VUV light of 147 nm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.697-699
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• 2009

Optical properties of white organic light-emitting devices (WOLEDs) fabricated utilizing a phosphor layer acting as a color conversion layer were investigated. The WOLEDs were achieved due to the enhancement in the color conversion efficiency of the phosphor layer, and the chromaticity coordinates of WOLEDs were (0.29, 0.33).

• 한국세라믹학회지
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• 제52권4호
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• pp.229-233
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• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.614-619
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• 2013

Recently, remote phosphor is reported for white LED enhancing of phosphor efficiency compared with conventional phosphor-based W-LED. In this study, Remote phosphor was produced by screen printing coating on glass substrate with phosphor contents rated paste and heat treatment. The paste consists of phosphor, lowest softening glass frit and organic binders. Remote phosphor can be well controlled by varying the phosphor content rated paste. After mounting remote phosphor on top of blue LED chip, CCT, CRI, and luminance efficiency were measured. The measurement results showed that CCT, CRI, and luminance efficiency were 6,645, 68, and 1,16l m/W in phosphor 80 wt.% remote phosphor sintered at $600^{\circ}C$.

• Korean Chemical Engineering Research
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• 제43권3호
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• pp.407-411
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• 2005

분무용액에 다양한 융제들을 도입하여 분무열분해법에 의해 YAG:Tb($Y_3Al_5O_{12}:Tb$) 형광체들을 합성하였다. 융제의 종류, 유기 첨가물 및 후열처리 온도 등이 YAG:Tb 형광체의 형태, 결정성 및 발광 특성에 미치는 영향 등을 조사하였다. 유기첨가물로 사용된 구연산과 에틸렌 글리콜은 고온의 열처리 과정에서 YAG:Tb 형광체의 형태 파괴 없이 발광 특성을 증대시켰다. 반면에 다량의 융제를 포함한 분무용액으로부터 분무열분해 공정에 의해 합성된 전구체 분말은 $1300^{\circ}C$에서의 후열처리 후에 구형의 형태가 사라졌다. 리튬 탄산염을 융제로 함유한 분무용액으로부터 합성된 YAG:Tb 형광체는 후열처리 후에 미세하면서도 균일한 형태를 가졌다. 융제로서 사용된 리튬 탄산염은 YAG:Tb 형광체의 발광 휘도 개선에도 효과적이었다. 리튬 탄산염을 융제로 첨가한 경우에 합성된 YAG:Tb 형광체의 최적의 발광 세기는 융제를 첨가하지 않은 경우에 합성된 형광체의 발광세기의 189％였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.178-181
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100 %, compared to 25 % in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)$_3$ (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(PPy)$_3$ doped in the host material/BCP/Alq$_3$/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(PPy)$_3$ and the host materials, we fabricated several devices and investigated the device characteristics.

• 한국세라믹학회지
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• 제50권6호
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• pp.454-459
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• 2013

Recently, remote phosphors have been reported for application to white LEDs to provide enhanced phosphor efficiency compared with conventional phosphor-based white LEDs. In this study, a remote phosphor was produced by coating via screen printing on a glass substrate with different numbers of phosphor coating. The paste consists of phosphor, lowest softening glass frits, and organic binders. The remote phosphor could be well controlled by varying the phosphor content rated paste. After mounting the remote phosphor on top of a blue LED chip, CCT, CRI, and luminance efficiency were measured and values of 5300 K, 62, and 117 lm/W were respectively obtained in the 80 wt% phosphor with 3 coating layers sintered at $800^{\circ}C$.

• Korean Chemical Engineering Research
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• 제48권1호
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• pp.75-79
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• 2010

에틸렌디아민테트라아세트산, 구연산 및 $NH_4Cl$ 융제가 첨가된 분무용액으로부터 분무열분해법에 의해 얇은 막 구조의 전구체 분말들을 합성하였다. $1,200^{\circ}C$에서 소성 과정을 거친 유기 첨가제와 융제를 사용하지 않은 $BaMgAl_{10}O_{17}:Eu$ 형광체는 $1{\sim}5{\mu}m$ 크기의 구형이며, 두꺼운 막 형태의 속이 빈 구조를 가졌다. 반면에 에틸렌디아민아세트산과 구연산을 첨가하여 합성된 BAM:Eu 형광체는 판상 구조의 미세한 크기를 가졌다.$NH_4Cl$ 융제의 첨가량이 0, 6, 35 wt%일때 합성된 미세 형광체들의 결정자 크기는 각각 23, 35, 33 nm였다. 최대의 발광 세기를 나타내는 최적의 융제 첨가량은 형광체의 35 wt%였으며, 융제를 첨가하지 않은 분무용액으로부터 합성된 형광체의 발광 세기의 215%였다.