• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.323-326
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• 2009

We have developed blue-emitting phosphorescent organic light emitting diodes (OLEDs) using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tris (8-quinolinolato)aluminum ($Alq_3$) electron transport layers. As blue dopant and host materials, bis[(4,6-di-fluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) and N,N'-dicarbazolyl-3,5-benzene (mCP) were used, respectively. The driving voltage, current efficiency and emission characteristics of devices were investigated. While the driving voltage was about $1{\sim}2$ V lower in the device with an $Alq_3$ layer, the current efficiency was about 66 % higher in the device with BCP electron transport layer. the blue phosphorescent OLED with BCP layer exhibited higher purity of color, resulting from a relatively weak electroluminescence intensity at 500 nm.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.7-10
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• 2003

Blue-light-emitting peiymer/dielectric nanolayer nanocomposites were prepared by the solution intercalation method and employed in electroluminescent device. Their photoluminescence and electroluminescence characteristics suggested that the nanolayers isolate the polymer chains and hinder the formation of excimers and aggregates. By reducing the excimer formation and its deleterious effects on emission efficiency, both the color purity and the luminescence stability were improved. Furthermore, the dielectric nanolayers have an aspect ratio of about 500 and therefore act as efficient barriers to oxygen and moisture diffusion, which produced a dramatic increase in the device stability.

• Journal of Information Display
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• v.8 no.1
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• pp.10-13
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• 2007

We synthesized new blue and bluish green emitting materials by using fully substituted ethylene moieties. Multi-layered EL devices were fabricated with synthesized materials and evaluated in terms of emission color and luminescence efficiency. TBBPE[EML 2] device showed bluish-green CIE value of (0.236, 0.412) and 5.02cd/A at $10mA/cm^2$. BPBBPE[EML 3] device also showed sky-blue CIE value of(0.218, 0.355) and 2.31cd/A at $l0mA/cm^2$.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2884-2888
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• 2010

Two red fluorescent DCJTB derivatives (Red 1 and 2) based on modified pyrans were synthesized and their electroluminescent properties were investigated. Multilayered OLEDs were fabricated with the device structure of ITO/NPB (40 nm)/Red 1, 2 or DCJTB (0.5 or 1%): $Alq_3$ (20 nm)/$Alq_3$ (40 nm)/Liq (2 nm)/Al. All devices exhibited efficient red emissions. In particular, a device containing emitter Red 2 as a dopant in the emitting layer, the maximum luminance was $8737\;cd/m^2$ at 12.0 V, the luminous and power efficiencies were 2.31 cd/A and 1.25 lm/W at $20\;mA/cm^2$, respectively. The peak wavelength of the electroluminescence was 638 nm with the CIE (x,y) coordinates of (0.63, 0.36) at 7.0 V.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1418-1421
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• 2009

A series of new light-emitting random copolymers with fully conjugated structure was prepared, for the first time through the well-known Gilch polymerization between 1,4-bis(chloromethyl)-2-ethylhexyloxy-5-methoxybenzene and 2,5-bis(bromomethyl)thiophene monomers in different ratios. The synthesized polymers (on thin film) showed the maximum wavelength of UV-visible absorbance and photoluminescence (PL) near 500 nm and near 600 nm, respectively. A single-layer light-emitting diode device, which has a simple ITO (indium-tin oxide)/polymer/Al configuration, was fabricated by spin-coating of polymers and then vacuum evaporation of Al metal. The threshold bias of PMEHPVTVs was in the range of 3.5-10 V. As in the PL spectra, the maximum wavelength of light emission near 600 nm was also shown in electroluminescence (EL) spectra of PMEHPVTVs when the operating voltage was about 7 - 14 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.286-290
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• 1999

Electroluminescence is occurred when phosphor is located in electric field. In this paper, we made powder electroluminescent device (PELD) with structured ITO film/Phosphor/Insulator/Silver paste. The transparent electrode was ITO film and green(2704-01), orange(2702-02) and blue-green(2703-01) were used as phosphor. The insulator was BaTiO$_3$ and $Y_2$O$_3$, back electrode was silver paste. To investigate electrical and optical properties of PELDs, EL spectrum, Brightness, Transferred charge density using Sawyer-Tower\`s circuit was measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.228-235
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• 2004

In this thesis, it is designed efficient electrode formation on the organic luminescent device. ITO electrode is treated with $O_2$plasma. In order to inject hole efficiently, there is proposed the shape of anode that inserted plasma polymerized films as buffer layer between anode and organic layer using thiophene monomer. It is realized efficiently electron injection to aluminum due to introduce the quantum well in cathode. In the case of device inserted the buffer layer by using the plasma poiymerization after $O_2$plasma processing for ITO transparent electrode, since it forms the stable interface and reduce the moving speed of hole, the recombination of hole and electronic ate made in the omitting layer. Compared with the devices without buffer layer, the turn-on voltage was lowered by 1.0(V) doc to the introduction of buffer layer Since the quantum well structure is formed in front of cathode to optimize the tunneling effect, there is improved the power efficiency more than two times.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.582-585
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• 1999

Electroluminescence is occurred when phosphor is located in electric field. In this paper, we made powder electroluminescent device (PELD) with structured ITO film/Phosphor/Insulator/Silver paste. The transparent electrode was ITO film and green(2704-01) and orange(2702-02) and blue-preen(2703-01) were used as phosphor. The insulator was BaTiO$_3$ and $Y_2$O$_3$, bark electrode was silver paste. To investigate electrical and optical properties of PELDs, EL spectrum, Brightness . Transferred charge density using Sawyer-Towers circuit was measured.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.752-758
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• 1995

Red emitting CaS:Eu,S electroluminescent(EL) device prepared at 550.deg. C by an electron-beam evaporation technique, demonstrated luminance of 175cd/m$\^$2/ and efficiency of 0.311m/W with 3kHz drive. Luminance was increased with the increase of applied voltage and frequency. From the results of the PL spectrum and the EL spectrum, the CaS:Eu, S device showed emission peak near 640nm resulted from the transition of EU$\^$2+/ 4f$\^$6/5d.rarw.4f$\^$7/. The capacitance of the phosphor layer from the Sawyer-Tower circuit was 10.5nF/cm$\^$2/.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.166-169
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• 2000

The Organic Electroluminescence (OEL) device, that was consisted of ALq3(8-hydroxyquinoline aluminum) and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine), has been used. We investigated characteristics of brightness and current density about OEL that was oxidated each layers. We used two samples that were fabricated each continuous and non-continuous method. Emission was observed above 10mA/$\textrm{cm}^2$ and luminance was measured to be 1530cd/$\textrm{cm}^2$ at a current density of 100mA/$\textrm{cm}^2$. A luminance of over 2600cd/$\textrm{cm}^2$ was also observed after the final fabrication process.