• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.324-325
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• 2006

In order to develop high efficiency white organic light-emitting diodes (OLEDs), OLED devices consisted of red and blue emitting layers (EMLs) were fabricated and the effect of respective layer thickness and the order of layer stacking on the luminous efficiency was evaluated Red/blue structure showed higher efficiency than blue/red, due to the higher exiton formation. In the blue layer of red/blue structure. However, the efficiency of the red/blue significantly depended on the thickness of the red layer, whereas the thickness of the blue layer was not affect so much. The optimum thickness of the red layer was 20 ${\AA}$, where the luminous and power efficiencies were 155 cd/A and 10.51 lm/W at 1000~3000$cd/m^2$ respectively and the maximum luminance was about 80,000 $cd/m^2$.

• 한국표면공학회지
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• 제48권3호
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• pp.115-120
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• 2015

We studied white tandem organic light-emitting diodes using red and blue fluorescent materials. White 2 units tandem OLEDs were fabricated using $Alq_3$:Rubrene (3 vol.% 5 nm) and SH-1 : BD-2 (3 vol.% 25 nm) as emitting layer (EML). The device with $Alq_3$ : Rubrene (3 vol.% 5 nm) / SH-1 : BD-2 (3 vol.% 25 nm) showed yellowish white emission with a Commission Internationale de l'Eclairage (CIE) coordinates of (0.442, 0.473) at $1,000cd/m^2$, and variation of CIE coordinates was low with ($0.44{\pm}0.002$, $0.472{\pm}0.001$) from 500 to $3,000cd/m^2$. White 3 units tandem OLEDs were fabricated by additory stacking the blue or white layer as EML. CIE coordinates of 3 units tandem OLEDs with stacked blue and white layer was low variation of ($0.293{\pm}0.008$, $0.36{\pm}0.005$) and ($0.412{\pm}0.002$, $0.423{\pm}0.001$) from 500 to $3,000cd/m^2$, respectively. Our findings suggest that stacked OLED was possible to controlling CIE coordinates and producing excellent color stability.

• 공업화학
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• 제34권1호
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• pp.94-97
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• 2023

BTPSF와 BDTSF는 유기발광다이오드용 스파이로플루오렌 모이어티를 기반으로 하는 새로운 청색 발광 물질로 성공적으로 합성되었다. BTPSF와 BDTSF는 촉매를 사용하지 않고 Diels-Alder 반응을 통해 합성하여 고순도를 얻었다. 합성된 물질의 광발광 스펙트럼은 용액 상태에서 약 381, 407 nm, 필름 상태에서 각각 395, 434 nm의 최대 발광 파장을 나타내어 자외선과 짙은 청색 발광색을 나타냈다. 합성된 BDTSF 물질은 non-doped 소자의 EML로 적용되었으며, 전류 효율은 0.61 cd/A이다.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.456-461
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• 2012

We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with red/blue, blue/red and red/blue/red emitting layer (EML) structures were fabricated using a host-dopant system. In case of white PHOLEDs with red/blue structure, the best efficiency was obtained at a structure of red (15 nm)/blue (15 nm). But the emission color was blue-shifted white. In case of white PHOLEDs with blue/red structure, the better color purity and efficiency were observed at a blue (29 nm)/red (1 nm) structure. For additional improvement of color purity in white PHOLEDs with blue (29 nm)/red (1 nm) EMLs, we fabricated white PHOLEDs with red (1 nm)/blue (28 nm)/red (1 nm) structure. The current efficiency, external quantum efficiency, and CIE (x, y) coordinate were 27.2 cd/A, 15.1%, and (0.382, 0.369) at 1,000 $cd/m^2$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1046-1049
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• 2002

In this study, We fabricated Organic Electroluminescence device, in order to improve the efficiency of Blue OLED in the full-color OLED. We made two sample. Sample A is that We used TPD(N,N‘-bis(3-methylphenyl)-N,N'-diphenylbenzidine} as hole transport layer(HTL), and Butyl-PBD(2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole) as emitting material layer(EML) and Alq3(8-Hydroxyquinoline, aluminum} as electron transport layer(ETL). Sample B is that we used TPD(N, N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine} as HTL and co-evaporated Butyl-PBD and Alq3 as EML. We investigated the characteristic of brightness and current-:voltage. The sample B that co-evaporated Butyl-PBD and Alq3 as EML improved characteristic of brightness and current-voltage than sample A. Maximum luminescence of sample B is $310cd/m^2$ and threshold voltage is 7V.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.526-529
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• 2008

By combining tetraphenylethylene and anthracene, we synthesized 9,10-bis(4-(1,2,2-triphenylvinyl)phenyl) anthracene [BTPPA] and 1,2-di(4'-tert-butylphenyl)-1,2-bis(4'-(anthracene-9-yl)phenyl)ethene [BPBAPE]; both BTPPA and BPBAPE have similar band-gaps, however their PL spectra were shifted by about 30 nm with respect to each other. The fabricated multilayered non-doped OLED devices based on pure BTPPA or BPBAPE exhibited luminance efficiencies of 3.93 cd/A at 6.8 V and 10.33 cd/A at 8.1 V, respectively, at $10\;mA/cm^2$. As the BPBAPE content of the emitting layer increased, the luminance efficiency of the device increased; in addition, the CIE coordinates of the fabricated devices shifted gradually from deep-blue for pure BTPPA to sky-blue for pure BPBAPE.

• Journal of Information Display
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• 제10권3호
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• pp.107-110
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• 2009

Efficient deep-blue organic light-emitting diodes were demonstrated using 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl doped in double-emission layers (D-EMLs). The D-EML system, which consists of 2-methyl-9,10-di(2-naphthyl)anthracene and 1,4-(dinaphthalen-2-yl)-naphthalene as blue hosts, was employed to broaden the recombination zone and to ensure the good confinement of the holes and electrons. The optimized device showed a peak current efficiency of 4.47 cd/A, a peak external quantum efficiency of 4.09%, and Commission Internationale de L'Eclairage coordinates of (0.16, 0.10).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.411-414
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• 2009

We report single and two-stacked WOLED. Two-stacked WOLED structure adopts fluorescent blue EML and phosphorescent (red+green) EML. Current efficiency, EQE and color coordinate of two-stacked WOLED are 54.5cd/A, 28.8% and CIExy (0.322, 0.345), respectively. Those of single WOLED are also 20cd/A, 10% and CIExy (0.29, 0.37), respectively. Dual-plate OLED Display (DOD) employing the single WOLED shows high aperture ratio up to 67% in 2-inch panel of which pixel size is equivalent to that of 32 inch Full HD.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.853-858
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• 2008

The structure of organic light-emitting diodes(OLEDs) with typical heterostructure consists of anode, hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, and cathode. 4,4bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl(NPB) used as a hole transport layer and 4'4-bis(2,2'-diphenyl vinyl)-1,1'-biphenyl(DPVBi) used as a blue light emitting layer were graded-mixed at selected ratio. Interface at heterojunction between the hole transport layer and the elecrtron transport layer restricts carrier's transfer. Mixing of the hole transport layer and the emitting layer reduces abrupt interface between the hole transport layer and the electron transport layer. The operating voltage of OLED devices with graded mixed-layer structure is 2.8 V at 1 $cd/m^2$ which is significantly lower than that of OLED device with typical heterostructure. The luminance of OLED devices with graded mixed-layer structure is 21,000 $cd/m^2$ , which is much higher than that of OLED device with typical heterostructure. This indicates that the graded mixed-layer enhances the movement of carriers by reducing the discontinuity of highest occupied molecular orbital(HOMO) of the interface between hole transport layer and emitting layer.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1381-1382
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• 2005

We report improved efficiency in blue electrophosphorescent organic light emitting diodes by introducing an interfacial exciton blocking layer between light emitting layer (EML) and hole transport layer (HTL). Iridium(III) bis [(4,6-di-fluorophenyl)- pyridinato -N,C2']picolinate (FIrpic) was used as blue phosphorescent dopant and JHK6-3 with carbazole and electron transporting group as host and also as the interfacial layer, resulting in drastic increase in quantum efficiency.