• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.437-441
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• 2006

The red emitting OLEDs using $Alq_3$:Rubrene-GDI4234 phosphors have been fabricated and characterized . In the device fabrication, 2- TNATA [4,4',4' - tris (2- naphthylphenyl - phenylamino ) - tripheny lamine] as the hole injection material and NPB [N,N'-bis (1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as the hole transport material were deposited on the ITO(indium tin oxide)/glass substrate by vacuum evaporation. And then, red color emissive layer was deposited using $Alq_3$ as the host material and Rubrene(5,6,11,12-tetraphenylnaphthacene)-GDI4234 as the dopants. finally, small molecule OLEDs with structure of ITO/2-TNATA/NPB/$Alq_3$:Rubrene-GDI4234/$Alq_3$/LiF/Al were obtained by in-situ deposition of $Alq_3$, LiF and Al as the electron transport material, electron injection material and cathode, respectively. Red OLEDs fabricated in our experiments showed the color coordinate of CIE(0.65, 0.35) and the maximum power efficiency of 2.1 lm/W at 7 V with the peak emission wavelength of 632 nm.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.51-55
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• 2006

The green emitting high performance OLEDs using the $Alq_3$-C545T fluorescent system have been fabricated and characterized. In the device fabrication, 2-TNATA [4,4',4'-tris(2-naphthylphenyl-phenylamino)-triphenylamine] as a hole injection material and NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as a hole transport material were deposited on the ITO(indium thin oxide)/glass substrate by vacuum evaporation. And then, green color emission layer was deposited using $Alq_3$ as a host material and C-545T[10-(2-benzothiazolyl)-1,1,7,7- tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]/benzopyrano[6,7,8-ij]-quinolizin-11-one] as a dopant. Finally, small molecule OLEDs with structure of ITO/2-TNATA/NPB/$Alq_3$:C545T/$Alq_3$/LiF/Al were obtained by in-situ deposition of $Alq_3$, LiF and Al as the electron transport material, electron injection material and cathode, respectively. Green OLEDs fabricated in our experiments showed the color coordinate of CIE(0.29, 0.65) and the maximum power efficiency of 7.3 lm/W at 12 V with the peak emission wavelength of 521 nm.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.93-97
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• 2013

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 co-doping and blue/co-doping emitting layer (EML) structures were fabricated using a host-dopant system. The total thickness of light-emitting layer was 25 nm and the dopant of blue and red was FIrpic and $Bt_2Ir(acac)$ in UGH3, respectively. In case of co-doping structure, applying micro lens array film showed efficiency improvement from the current efficiency 78.5 cd/A and power efficiency 40.4 lm/W to the current efficiency 131.1 cd/A and power efficiency 65 lm/W and blue / co-doping structure showed efficiency improvement from the current efficiency 43.8 cd/A and power efficiency 22 lm/W to the current efficiency 69 cd/A and power efficiency 32 lm/W.

• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.7-11
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• 2008

ITO (Indium Tin Oxide) thin films have been extensively studied for OLED devices because they have high transparent properties in the visible wavelength and a low electrical resistivity. These ITO films are deposited by rf-magnetron sputtering under different ambient gases (Ar, Ar+$O_2$ and Ar+$H_2$) at $300^{\circ}C$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon has been changed from 0.5sccm to 5sccm and from 0.01sccm to 0.25sccm respectively. The resistivity of ITO film increased with increasing flow rate of $O_2$ under Ar+$O_2$ while it is nearly constant under Ar+$H_2$. And the peak of ITO films obtained (222) and (400) orientations and the average transmittance was over 80% in the visible range. The OLED device fabricated with different ITO substrates made by configuration of ITO/$\alpha$-NPD/Alq3/LiF/Al to elucidate the performance of ITO substrate for OLED device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.309-310
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• 2005

In the fabrication of high performance red organic light emitting diode, 2-TNA TA [4,4',4" -tris (2-naphthylphenyl- phenylamino)-triphenylamine] as hole injection material and N PH [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 vacuum evaporation, And then, red color emission layer was deposited using Alq3 as a host material and Rubrene (5,6,11,12- tetraphenylnaphthacene) and GDI 4234 as dopants. Finally, small molecular weight OLED with the structure of ITO/2-TNATA/ NPB/Alq3+Rubrene+GDI4234/Alq3/LiF/Al was obtained by in-situ deposition of Alq3, LiF and Al as electron transport material, electron injection material and cathode. respectively. Green OLED fabricated in our experiments showed the color coordinate of CIE(0.65,0.35) and the maximum luminescence efficiency of 2.1 lm/W at 7 V with the peak emission wavelength of 632 nm.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.50-56
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• 2007

Femtosecond laser ablation of the Invar alloy and hole drilling for a shadow mask are studied. We used a regenerative amplified Ti-sapphire laser with a 1kHz repetition rate, 184fs pulse duration and 785nm wavelength. Femtosecond laser pulse was irradiated on the Invar alloy with air blowing at the condition of various laser peak power. An ablation characteristic of the Invar alloy was appeared non-linear at $125J/cm^2$ of energy fluence. For the application to a shadow mask, the hole drilling of the Invar alloy with the cross section of a trapezoidal shape was investigated. The ablated micro-holes were characterized using an atomic force microscopy(AFM). The optimal condition of hole pattern f3r a shadow mask was $4\;{\mu}m$ z-axis feed rate, 0.2mm/s circular velocity, $26.4{\mu}J$ laser peak power. With the optimal processing condition, the fine circular hole shape without burr and thermal damage was achieved. Using the femtoseocond laser system, it demonstrates excellent tool for the Invar alloy micro-hole drilling without heat effects and poor edge.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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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.

• Korean Journal of Materials Research
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• v.21 no.4
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• pp.212-215
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• 2011

New organic light-emitting diodes with structure of indium-tin-oxide[ITO]/N,N'-diphenyl-N, N'-bis-[4-(phenyl-m-tolvlamino)-phenyl]-biphenyl-4,4'-diamine[DNTPD]/1,1-bis-(di-4-poly-aminophenyl) cyclohexane[TAPC]/bis(10-hydroxy-benzo(h)quinolinato)beryllium[Bebq2]/Bebq2:iridium(III)bis(2-phenylquinoline-N,C2')acetylacetonate[(pq)2Ir(acac)]/ET-137[electron transport material from SFC Co]/LiF/Al using the selective doping of 5%-(pq)2Ir(acac) in a single Bebq2 host in the two wavelength (green, orange) emitter formation were proposed and characterized. In the experiments, with a 300${\AA}$-thick undoped emitter of Bebq2, two kinds of devices with the doped emitter thicknesses of 20${\AA}$ and 40${\AA}$ in the Bebq2:(pq)2Ir(acac) were fabricated. The device with a 20${\AA}$-thick doped emitter is referred to as "D-1" and the device with a 4${\AA}$-thick doped emitter is referred to as "D-2". Under an applied voltage of 9V, the luminance of D-1 and D-2 were 7780 $cd/m^2$ and 6620 $cd/m^2$, respectively. The electroluminescent spectrum of each fabricated device showed peak emissions at the same two wavelengths: 508 nm and 596 nm. However, the relative intensity of 596 nm to 508 nm at those wavelengths was higher in the D-2 than in the D-1. The D-1 and D-2 devices showed maximum current efficiencies of 5.2 cd/A and 6.0 cd/A, and color coordinates of (0.31, 0.50) and (0.37, 0.48) on the Commission Internationale de I'Eclairage[CIE] chart, respectively.

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.39-43
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• 2022

In optoelectronic devices including displays and solar cells that convert electricity into light or light into electricity, it is important to control optical behavior of light to improve device efficiency. Specifically, the control of internal emitting light in the OLEDs can induce more light to go out, improving luminous efficiency. In addition, the control of optical behavior of incident light in solar cells can increase optical path in the light absorption layer, increasing power-conversion efficiency. In this study, we generated wrinkles as a physical structure to control optical behavior of light and independently controlled their wavelength and height by changing stress relaxation time. To explore the effect of wavelength and height on optical behavior, we conducted UV/Vis spectroscopy analysis of wrinkles with various heights at a constant wavelength or various wavelengths at a comparable height, figuring out a wrinkle with high aspect ratio has more dispersive light and less straight light. It indicates that high aspect ratio is required to change the optical behavior and increase the optical path.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.1-6
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• 2008

New devices with the structure of ITO/2-TNATA/NPB/TCTA/CBP:$7%Ir(ppy)_3$/BCP/SFC-137/LiF/Al were designed and fabricated to develop high efficiency green phosphorescent organic light emitting diodes and their electroluminescence properties were evaluated. Among the devices with different thicknesses of CBP in a range of $150{\AA}{\sim}350{\AA}$, the best luminance was obtained in the device with $300{\AA}$-thick CBP host. Nearly saturated current efficiencies indicates that the maximum efficiency value can be obtained with CBP thicknesses of $300{\AA}{\sim}350{\AA}$. The current density, luminance, and current efficiency of the PhOLED(phosphorescent organic light emitting diode) with $CBP(300{\AA}):7%Ir(ppy)_3-emissive$ layer at an applied voltage of 10V were $40mA/cm^2,\;10000cd/m^2$, and 25 cd/A, respectively. The maximum current efficiency was 40.5cd/A under the luminance of $160cd/m^2$. The peak wavelength and FWHM(full width at half maximum) in the electroluminescence spectral were 512nm and 60nm, respectively. The color coordinate was (0.28, 0.63) on the CIE (Commission Internationale de I'Eclairage) chart.