• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.155-155
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• 2010

We have investigated organic light-emitting devices by doping phosphorescent orange and fluorescent blue emitters into the separate layers of single host. The electroluminescence spectra and current efficiency were strongly dependent on the location of each doped layers. The luminance-voltage (L-V) characteristics of the device2 (ITO/Hole Transport Layer/Orange Phosphorescent emissive layer/Blue Fluorescent emissive layer/Electron Transport Layer/liF/Al) showed the maximum current efficiency of 19.5 cd/A.

• 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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• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.366-369
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• 2001

In this study, the matrix Organic Electroluminescence (OEL) device, that was consisted of R,G,B pixels. We fabricated OEL devices by side by side methode and, used organic material Alq3 as green, DCM as red and Butyl PBD as blue ETL. We investigated the characteristic of brightness and current density for matrix OEL device. As the results, each color devices has minimum about $100cd/m^{2}$ brightness and maximum luminescence was $2500cd/m^2$ in green OEL device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.366-369
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• 2001

In this study, the matrix Organic Electroluminescence (OEL) device, that was consisted of R,G,B pixels. We fabricated OEL devices by side by side methode and, used organic material Alq3 as green, DCM as red and Butyl PBD as blue ETL. We investigated the characteristic of brightness and current density for matrix OEL device. As the results, each color devices has minimum about 100 cd/㎡ brightness and maximum luminescence was 2500cd/㎡ in green OEL device

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.163-168
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• 2009

Hyperbranched conjugated polymers (p-HPPV and m-HPPV) with para and meta linkages were synthesized from $A_2$ and $B_4$ type monomers through Wittig polycondensation. The synthesized p-HPPV and m-HPPV were completely soluble in common organic solvents such as chloroform, tetrahydrofuran, 1,2-dichloroethane, etc. and thermal gravimetric analyses showed that p-HPPV and m-HPPV are stable up to $350^{\circ}C$. The molecular weights (from GPC), UV-visible, and photoluminescence maximum peaks of p-HPPV and m-HPPV are characterized in detail. The fabricated EL devices using the synthesized hyperbranched polymers, (ITO/(p-HPPV or m-HPPV)/Al), showed EL emission at about 507 nm and 481 nm (681 nm), respectively. Especially, EL device from m-HPPV were found to exhibit nearly white emission with approximate CIE coordinates of (0.31, 0.34) compared with (0.310, 0.316) of NTSC white color at $100\;cd/m^2$. The good photophysical properties combine with good film-form ability could make these hyperbranched polymers to be a potential candidate for the EL materials.

• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.189-197
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• 2002

The color stability and purity from OLED is of current interest. Aggregation of dyes alters the device color after fabrication of the devices. Exciplex and electroplex formations have been proposed to explain the aggregate color change. We investigate the possibility of exciplex formation and propose the new electroplex state that can cause the bathochromic shift of the electroluminescence spectrum from the devices with TPD/PBD layers. The photoluminescence maximum of the device was 420nm, and the electroluminescence maximum of the device to became 480nm. The bathochromic shift cannot be attained with photoluminescence study with highly concentrated TPD/PBD mixture. This clearly indicates that the 480nm spectrum of the devices is not resulted from the exciplex formation with TPD and PBD. We observed the overshoot in EL spectrum from the OLEDs. The most intense overshoot was observed at 460nm, which may be due to the aggregates that are formed after the electric field has been removed from the devices.

• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.91-106
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• 2008

Development of white light emitting materials has been an interesting area for scientists and scientists have developed many organic, polymer and inorganic materials for white electroluminescent devices. Among them, single component small molecules gave best results in terms of efficiency, simplicity of device fabrication, and CIE values. Therefore, this review covers detailed discussion about syntheses of small compounds used in white organic light emitting devices until 2007.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1343-1346
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• 2005

Self assembled monolayers (SAM) are generally used at the anode/organic interface to enhance the carrier injection in organic light emitting devices, which improves the electroluminescence performance of organic devices. This paper reports the use of SAM of 1-decanethiol (H-S(CH2)9CH3) at the cathode/organic interface to enhance the electron injection process for organic light emitting devices. Aluminum (Al), tris-(8-hydroxyquionoline) aluminum (Alq3), N,N'-diphenyl-N,N'-bis(3 -methylphenyl)-1,1'- diphenyl-4,4'-diamine (TPD) and indium-tin-oxide (ITO) were used as bottom cathode, an emitting layer (EML), a hole-transporting layer (HTL) and a top anode, respectively. The results of the capacitancevoltage (C-V), current density -voltage (J-V) and brightness-voltage (B-V), luminance and quantum efficiency measurements show a considerable improvement of the device performance. The dipole moment associated with the SAM layer decreases the electron schottky barrier between the Al and the organic interface, which enhances the electron injection into the organic layer from Al cathode and a considerable improvement of the device performance is observed. The turn-on voltage of the fabricated device with SAM layer was reduced by 6V, the brightness of the device was increased by 5 times and the external quantum efficiency is increased by 0.051%.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.543-547
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• 2005

Organic electroluminescence devices were made from 1,4-bis-(9-anthrylvinyl)benzene (AVB) and 1,4-bis-(9-aminoanthryl)benzene (AAB) anthracene derivatives. Device structure was ITO/AVB/PANI(EB)/Al (multi-layer device) and ITO/AAB:DCM/Al(single-layer device). In these devices, AVB, polyaniline(emeraldine base) (PANI(EB)) and AAB were used as the emitting material. 4-(dicyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H -pyran(DCM) was used as red fluorescent dopant. We studied change of fluorescence wavelength with concentration of DCM doped in AAB. The ionization potential (IP) and optical band gap (Eg) were measured by cyclic voltammetry and UV-visible spectrum. We compared with difference of emitting wavelength between photoluminescence and electroluminescence spectrum. In case of the multi-layer device, PANI and AVB EL spectra have similar wave pattern to each PL spectrum and when PAM and AVB were used at the same time, and multi-layer device showed that a balanced recombination and radiation kom PANI and AVB. In case of the single-layer device, with the increase of DCM concentration, the blue emission decreases and red emission increases. This indicates that DCM was excited by the energy transfer from AAB to DCM or the direct recombination at the dopant sites due to carrier trapping, or both. The device with $1.0wt\%$ DCM concentration gave white light.