• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.469-472
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• 2008

New iridium complexes with 2-(3',5'-bis-trifluoromethylphenyl)-4-metoxypyridine [$(CF_3)_2ppyOMe$] were synthesized and characterized for blue phosphorescent materials. It was found that $Ir[(CF_3)_2ppyOMe]_2$(acac) gives blue emission at 471 nm with strong luminescence efficiency. We discuss the role played by electron withdrawing substituents and also how the ancillary ligand influences the emission peak.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.817-819
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• 2009

We have developed highly efficient blue phosphorescent organic light-emitting devices (PHOLEDs) with simplified architectures using new host materials. The Blue PHOLED with new host:FIrpic emitting layer exhibits a maximum luminance efficiency of 34 cd/A and a low operating voltage 5 V at a high luminance of 1212 cd/$m^2$.

• 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 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1440-1442
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• 2007

In this work, we have modeled and fabricated microcavity-enhanced OLED using the 1-dimensional distributed Bragg reflector model (DBR). Results show that simulated spectrum intensity of microcavity OLED increased more than 30% compared to the conventional OLED, by use of DBR with $TiO_2$ and $SiO_2$. Spectral change of green and blue emission was expected to give the deeper color. The experimental design and characterization as well as the matching with simulated properties were performed for microcavity OLED for actual application.

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

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.36-36
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• 2008

Organic light-emitting device (OLED) have become very attractive due to their potential application in flat panel displays. One important problem to be solved for practical application of full-color OLED is development of three primary color (Red, Green and Blue) emitting molecule with high luminous operation. Particularly, the development of organic materials for blue electroluminescence (EL) lags significantly behind that for the other two primary colors. For this reason, Flu-Si was synthesized and characterized by means of high-resolution mass spectro metry and elemental analyses. Flu-Si has the more wide optical band gap (Eg = 3.86) than reference material (Cz-Si, Eg = 3.52 eV). We measured the photophysical and electrochemical properties of Flu-Si. The HOMO-LUMO levels were estimated by the oxidation potential and the onset of the UV-Vis absorption spectra. The EL properties were studied by the device fabricated as a blue light emitting material with FIrpic.

• 한국응용과학기술학회지
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• 제34권3호
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• pp.562-567
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• 2017

The organic light-emitting diodes are fabricated with six anthracene derivatives containing simple substituents such as phenyl or naphthyl group. The device structure is as in the following: Indium tin oxide (ITO) (180 nm)/4,4-4,4',4"-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (2-TNATA) (30 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl-1-amino] biphenyl (NPB) (20 nm)/Emitting compound (30 nm)/2,2',2"-(1,3,5-Benzinetriyl)-tris (1-phenyl-1-H-benz-imidazole) TPBi (40 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). In the emitting layer the anthracene derivatives are used without any dopant. All the six devices show blue emissions. Among the tested diodes, the one with 9-(2-naphthyl)-10-(p-tolyl) anthracene (2-NTA) exhibited luminous efficiency, power and external quantum efficiencies of 3.26 cd/A, 0.98 lm/A, 2.8 % at $20mA/cm^2$.

• 한국전기전자재료학회논문지
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• 제19권4호
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• pp.379-385
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• 2006

A stacked white organic light-emitting diode (OLED) having a blue/orange emitting layer was fabricated by synthesizing nitro-DPVT, a new derivative of the blue-emitting material DPVBi on the market. The white-emission of the two-wavelength type was successfully obtained by using both nitro-DPVT for blue~emitting material, orange emission as a host material and Rubrene for orange emission as a guest material. The basic structure of the fabricated white OLED is glass/ITO/NPB$(200{\AA})$/nitro-DPVT$(100{\AA})$/nitro-DPVT:$Rubrene(100{\AA})/BCP(70{\AA})/Alq_3(150{\AA})/Al(600{\AA})$. To evaluate the. characteristics of the devices, firstly, we varied the doping concentrations of fluorescent dye Rubrene from 0.5 % to 0.8 % to 1.3 % to 1.5 % to 3.0 % by weight. A nearly pure white-emission was obtained in CIE coordinates of (0.3259, 0.3395) when the doping concentration of Rubrene was 1.3 % at an applied voltage of 18 V. Secondly, we varied the thickness of the NPB layer from $150{\AA}\;to\;200{\AA}\;to\;250{\AA}\;to\;300{\AA}$ by fixing doping with of Rubrene at 1.3 %. A nearly pure white-emission was also obtained in CIE coordinates of (0.3304, 0.3473) when the NPB layer was $250-{\AA}$ thick at an applied voltage of 16 V. The two devices started to operate at 4 V and to emit light at 4.5 V. The external quantum efficiency was above 0.4 % when almost all of the current was injected.

• 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.

• 한국표면공학회지
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• 제48권4호
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• pp.174-178
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• 2015

We studied emission characteristics for blue fluorescent dual-side emission OLED with Al cathode thickness variation. In the bottom emission OLED of Al cathode with 10, 15, 20, 25, 30, and 150 nm thickness, maximum luminance showed 36.1, 8,130, 9,300, 12,000, 13,000, and $12,890cd/m^2$, and maximum current efficiency showed 2, 8.8, 10, 10.5, 10.8, and 11.4 cd/A, respectively. The emission characteristics of the bottom emission seemed to be improved according to decrease of resistance as the thickness of Al cathode increase. In the top emission OLED of Al cathode with 10, 15, 20, 25, and 30 nm thickness, maximum luminance showed 4.3, 351, 131, 88.6, and $33.2cd/m^2$, and maximum current efficiency showed 0.23, 0.38, 0.21, 0.16, and 0.09 cd/A, respectively. It yielded the highest maximum luminance and maximum current efficiency in Al cathode thickness 15 nm. It showed a tendency to decrease as the thickness of Al cathode increase. The reason for this is due to decrease of transmittance with increasing of Al cathode thickness. The electroluminescent spectra of bottom and top emission OLED were not change.