• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.316-323
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• 2003

Zinc complexes with bis[2-(o-hydroxyphenyl) naphtol [1,2] oxazolato ligands (ZnPBO-4) and its derivatives (ZnPBO-S) were synthesized, and luminescent properties of these materials were investigated. Both the fluorescent emission band and electroluminescent emission band were discussed based on their ligand structure differences. The emission band found that it strongly depends on the molecular structure of introduced ligand. It was tuned from 446 nm to 491 nm by changing the ligand structures. Spreading of the ${\pi}$-conjugation in 2-(o-hydroxyphenyl) group gives rise to a blue shift. The EL properties also showed good consistency with their differences of ligand structure. Bright-blue EL emission with a maximum luminance of 3,100 $cd/m^2$ at 12V, current density, 575 $mA/m^2$ was obtained from the organic light-emitting diodes (OLEDs) using ZnPBO-4 as emitting layer. It was also found that the newly synthesized materials were suitable to be used as emitting materials in organic EL device.

• Journal of the Semiconductor & Display Technology
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• v.5 no.3 s.16
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• pp.23-27
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• 2006

Recently, Top emission organic light-emitting diode (TEOLED) has been attracted by their potential application for the development of flat panel display (FPD). We have fabricated the high luminance top emission organic-emitting diode (TEOLED) using dual cathode layer and three top emitting structure. These devices were characterized by electroluminescence (EL) and current density-voltage (J-V) measurements. After compared it with Au anode structure, luminance of the device using dual anode was better than using without Al device. Consequently, Al layers are very good candidates for a promising electron-injecting buffer layer for top emission light-emitting diode (TEOLED).

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.292-297
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• 2001

Zinc complexes with Bis[2-(o-hydroxyphenyl) benzothiazolato ligands (ZnPBS-0) and Bis[2- (o-hydroxynaphthyl) benzothiazolato ligands (ZnPBS-05) were synthesized, and luminescent properties of these materials were investigated. The emission band found that it strongly depends on the molecular structure of introduced ligand and was tuned from 525 nm to 535 nm by changing the ligand structures. Spreading of the ${\pi}-conjugation$ in 2-(o-hydroxyphenyl) group gives rise to a blue shift. On the other hand, spreading of the ${\pi}-conjugation$ in benzothiazole groups leads to a red shift. The EL properties also showed good consistency with their differences of ligand structure. Bright-blue EL emission with a maximum luminance of 8300 $cd/m^{2}$ at 11V was obtained from the organic light - emitting diodes (OLEDs) using ZnPBS-0 as emitting layer. It was also found that the newly synthesized materials were suitable to be used as emitting materials in organic EL device.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.511-514
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• 2008

2-wavelength type white OLED devices have been made consisted of two layers; a layer with blue light emitting DPVBi host and other EML layer with yellow emitting rubrene dopant. New method to get white emitting device has been suggested by varying thicknesses of the DPVBi layer. The ITO/2-TNATA($150{\AA}$)/NPB($350{\AA}$)/DPVBi($35{\AA}$)/DPVBi:rubrene (2wt%,$200{\AA}$)/DPVBi($100{\AA}$)/Alq_3($50{\AA}$)/LiF($5{\AA}$)/Al($1000{\AA}$) structure has showed optimum results in CIE coordinates of (0.3233, 0.33). OLED devices with this structure has properties of $1.2d/m^2$ at turn-on voltage of 3.9V and $1037cd/m^2$ at 7.9V. This structure has advantages of simple fabrication and easy to emit the white color.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.486-488
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• 2009

High efficiency deep blue and pure white phosphorescent organic light emitting diodes were developed using a new deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium (FCNIr). A high quantum efficiency of 9.1 % with a color coordinate of (0.15, 0.16) at 1,000 cd/$m^2$ was obtained in the deep blue device and a high quantum efficiency of 15.2 % with a color coordinate (0.30, 0.32) was obtained in the pure white organic light-emitting diodes. The quantum efficiency of the pure white device is the best quantum efficiency value reported in the pure white device up to now.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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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 $120^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.442-449
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• 2006

Electrical, optical, and structural properties of indium zinc oxide (IZO) films grown by a box cathode sputtering (BCS) were investigated as a function of oxygen flow ratio. A sheet resistance of $42.6{\Omega}/{\Box}$, average transmittance above 88% in visible range, and root mean spare roughness of $2.7{\AA}$ were obtained even in the IZO layers grown at room temperature. In addition, it is shown that electrical characteristics of the top-emitting organic light emitting diodes (TOLEDs) with the BCS grown-IZO top cathode layer is better than that of TOLEDs with DC sputter grown IZO top cathode, due to absence of plasma damage effect. Furthermore the effects of oxygen flow ratio in IZO films are investigated, based on x-ray photoelectron spectroscopy (XPS), ultra violet/visible (UV/VIS) spectro-meter, scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.217-222
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• 2004

The white-light-emitting organic LED(OLED) with two-wavelength was fabricated using the DPVBi of blue emitting material and a series of orange color fluorescent dye(Rubrene) by vacuum evaporation processes. The basic structure of white-light-emitting OLED was ITO/NPB(150$\AA$)/DPVBi/Rubrene/BCP(100$\AA$)/Alq$_3$(150$\AA$)/Al(600$\AA$). We analyzed the fabricated device through the changes of the DPVBi and Rubrene layer's thickness. We obtained the white-light-emitting OLED with white color light and the CIE coordinate of the device was (0.29, 0.33) at applied voltage of 13V when the thickness of DPVBi layer was 210$\AA$ and the thickness of Rubrene layer was 180$\AA$. At a current of 100㎃/$\textrm{cm}^2$, the quantum efficiency was 0.35％ and at a voltage of 20V, it was 0.405％.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.208-211
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• 2009

The authors have demonstrated the various characteristics of hybrid white organic light-emitting diodes (HWOLED) using fluorescent blue and phosphorescent red emitters. We also demonstrated that two devices showed different characteristics in accordance with thickness of the 4,4′-N,N′-dicarbazole-biphenyl (CBP) spacer (CS) inserted between the blue and the red emitting layer. It was found that the device with a CS thickness of 70 $\AA$ showed a current efficiency 2.5 times higher than that of the control device with a CS thickness of 30 $\AA$ by preventing the triplet Dexter energy transfer from the red to the blue emitting layer. The HWOLED with the CS thickness of 70 $\AA$ exhibited a maximum luminance of 24500 cd/$m^2$, a maximum current efficiency of 42.9 cd/A, a power efficiency of 37.5 lm/W, and Commission Internationale de I'Eclairage coordinates of (0.37, 0.42).

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.107-111
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• 2013

A new green-emitting material with donor-acceptor architecture, 3,7-bis(1'-phenylbenzimidazole-2'-yl)-10-phenylphenothiazine (BBPP) was synthesized and its thermal, optical, and electroluminescent characteristics were investigated. Organic light-emitting diodes (OLEDs) with four different multilayer structures were prepared using BBPP as an emitting layer. The optimized device with the structure of [ITO/2-TNATA (40 nm)/BBPP (30 nm)/TPBi (30 nm)/Alq3 (10 nm)/LiF (1 nm)/Al (100 nm)] exhibited efficient green emission. Enhanced charge carrier balance and electron mobility in the organic layers enabled the device to demonstrate a maximum luminance of 31,300 cd/$m^2$, a luminous efficiency of 6.83 cd/A, and an external quantum efficiency of 1.62% with the CIE 1931 chromaticity coordinates of (0.21, 0.53) at a current density of 100 mA/$cm^2$.