• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.402-403
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• 2007

High-efficiency white organic light-emitting diodes (WOLEDs) were fabricated with two emissive layers and a spacer was sandwiched between two phosphorescent dyes which were, bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) as the blue emission and bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate $((acppy)_2Ir(acac))$ as the red emission. This spacer effectively prevented a triple-triple energy transfer between the two phosphorescent emissive layers with blue and red emission that was showed a improved lifetime. The white device showed Commission Internationale De L'Eclairage $(CIE_{x,y})$ coordinates of (0.33, 0.42) at $22400\;cd/m^2$, a maximum luminance of $27300\;cd/m^2\;at\;0.388\;mA/cm^2$, and a maximum luminous efficiency of 26.9 cd/A.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2211-2214
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• 2013

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.975-978
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• 2001

A novel poly[9,10-diphenylanthracene-4',4"-ylenevinylene-3,6-(N-2-ethyl hexyl)carbazole] containing alternate diphenylanthracene and carbazole unit was synthesized by the Wittig reaction. The obtained polymer was soluble in common organic solvents and thermally stable up to 380 $^{\circ}C.$ The polymer gives rise to bright blue fluorescence both in solution and in thin solid films. The light emitted from the device (ITO/polymer/Al) was greenish-blue in color and clearly visible in daylight.

• 반도체디스플레이기술학회지
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• 제6권2호
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• pp.11-14
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• 2007

For the fabrication of blue color organic light emitting diodes(OLED) with a high performance, 2-TNATA [4,4',4"-tris (2-naphthylphenyl-phenylamino)-triphenylamine] as hole injection material and NPB [N,N'-bis (1-naphthyl) -N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as hole transport material were deposited on the ITO (indium tin oxide)/glass substrate by the vacuum thermal evaporation. After then, blue color emission layer was deposited using TPM-BiP[(4'-Benzoylferphenyl-4-yl)phenyl-methanone-Diethyl(biphenyl-4-ymethyl)phosphonate] and GDI602 as a light emitting organic material. Finally, the two kinds of OLEDs with the structure of $ITO/2-TNATA/NPB/TPM-BiP/Alq_3/LiF/Al and ITO/2-TNATA/NPB/GDI602/Alq_3/LiF/Al$ were prepared by in-situ deposition. The maximum current density and luminance were found to be about $588\;mA/cm^2\;and\;5239\;cd/m^2$ at 12V for the OLED sample with the structure of $ITO/2-TNATA/NPB/TPM-BiP/Alq_3/LiF/Al$. Color coordinate of blue OLED was x=0.18, y=0.18 (at llV) and the maximum current efficiency was 2.82 cd/A (at 6V) with the peak emission wavelength of 440 nm.

• Transactions on Electrical and Electronic Materials
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• 제10권1호
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• pp.28-30
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• 2009

We have studied organic layer-thickness dependent electrical and optical properties of bottom- and top-emission devices. Bottom-emission device was made in a structure of ITO(170 nm)/TPD(x nm)/$Alq_3$(y nm)/LiF(0.5 nm)/Al(100 nm), and a top-emission device in a structure of glass/Al(100 nm)/TPD(x nm)/$Alq_3$(y nm)/LiF(0.5 nm)/Al(25 nm). A hole-transport layer of TPD (N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine) was thermally deposited in a range of 35 nm and 65 nm, and an emissive layer of $Alq_3$ (tris-(8-hydroxyquinoline) aluminum) was successively deposited in a range of 50 nm and 100 nm. Thickness ratio between the hole-transport layer and the emissive layer was maintained to be 2:3, and a whole layer thickness was made to be in a range of 85 and 165 nm. From the current density-luminance-voltage characteristics of the bottom-emission devices, a proper thickness of the organic layer (55 nm thick TPD and 85 nm thick $Alq_3$ layer) was able to be determined. From the view-angle dependent emission spectrum of the bottom-emission device, the peak wavelength of the spectrum does not shift as the view angle increases. However, for the top-emission device, there is a blue shift in peak wavelength as the view angle increases when the total layer thickness is thicker than 140 nm. This blue shift is thought to be due to a microcavity effect in organic light-emitting diodes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.36-37
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• 2009

We have studied the effect of the hole transporting layers on the device efficiencies blue phosphorescent organic light emitting diodes (PHOLED) with of iridiumIIIbis4,6-di-fluorophenyl-pyridinato-N,C2picolinate (FIrpic) doped 3,5--N,N-dicarbazole-benzene (mCP) host. The highest efficiency of blue PHOLED is strongy dependent on the hole transporting materials, exhibiting the maximum current efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1377-1378
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• 1998

Blue light emitting electroluminescence(EL) diodes were fabricated utilizing Coronene and some organic materials. Coronene showed photoluminescence(PL) peak at 450nm in solution with high quantum efficiency. Multi layer system was applied to fabricate EL diode utilizing Coronene. The device showed didode-like applied voltage-current relationship. And blue light emitting was observed. The decay time of device was in a scale of some seconds. The trun-on voltage of device was about 9 V.

• 한국전기전자재료학회논문지
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• 제25권11호
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• pp.910-915
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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. The best blue emitting OLED and red emitting OLED characteristics were obtained at a concentration of 12 vol.% FIrpic and 1 vol.% $Bt_2Ir$(acac) in UGH3, respectively. And the optimum thickness of the total emitting layer was 25 nm. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with red/blue/red, blue/red, red/blue and co-doping emitting layer structures were fabricated using a host-dopant system. In case of white PHOLEDs with co-doping structure, the best efficiency was obtained at a structure UGH3: 12 vol. % FIrpic: 1 vol.% $Bt_2Ir$(acac) (25 nm). The maximum brightness, current efficiency, power efficiency, external quantum efficiency, and CIE (x, y) coordinate were 13,430 $cd/m^2$, 40.5 cd/A, 25.3 lm/W, 17 % and (0.49, 0.47) at 1,000 $cd/m^2$, respectively.

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.451-456
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• 2013

To study emission properties of white phosphorescent organic light emitting devices (PHOLEDs), we fabricated white PHOLEDs of ITO(150 nm) / NPB(30 nm) / TcTa(10 nm) / mCP(7.5 nm) / light-emitting layer(25 nm) / UGH3(5 nm) / Bphen(50 nm) / LiF(0.5 nm) / Al(200 nm) structure. The total thickness of light-emitting layer with co-doping and blue-doping/co-doping using a host-dopant system was 25 nm and the dopant of blue and red was FIrpic and $Bt_2Ir$(acac) in UGH3 as host, respectively. The OLED characteristics were changed with position and thickness of blue doping layer and co-doping layer as light-emitting layer and the best performance seemed in structure of blue-doping(5 nm)/co-doping(20 nm) layer. The white PHOLEDs showed the maximum current density of $34.5mA/cm^2$, maximum brightness of $5,731cd/m^2$, maximum current efficiency of 34.8 cd/A, maximum power efficiency of 21.6 lm/W, maximum quantum efficiency of 15.6%, and a Commission International de L'Eclairage (CIE) coordinate of (0.367, 0.436) at $1,000cd/m^2$.

• 한국응용과학기술학회지
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• 제26권3호
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• pp.357-361
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• 2009

The authors have demonstrated white oraganic light-emitting diodes (WOLED) using 1,4-bis[2-(4'-diphenylaminobiphenyl-4-yl)vinyl]benzene as fluorescent blue emitter and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate as phosphorescent red emitter. The optimized WOLED using red host material as bis(2-methyl-8-quinolinato) -4-phenylphenolate exhibited proper color stability in comparison with the control device using 4,4'-N,N'-dicarbazole-biphenyl as red host. The white device showed a maximum luminance of 21100 $cd/m^2$ at 14 V, luminous efficiency of 9.7 cd/A at 20 $mA/cm^2$, and Commission Internationale de I'Eclairage ($CIE_{x,y}$)coordinates of (0.32, 0.34) at 1000 $cd/m^2$. The devices also exhibited the color shift with ${\Delta}CIE_{x,y}$ coordinates of ${\pm}$ (0.01,0.01) from 100 to 20000 $cd/m^2$.