• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.40-44
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• 2017

The effect of weak dielectric silicone dioxide($SiO_2$) embedded in polyfluorene(PFO) emitting layer of polymer-based multi structure OLED was investigated. Indium tin oxide(ITO)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/poly(9,9-di-n-octylfluorenyl-2,7-diyl)(PFO)/2,2,2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi)/aluminum(Al) structure OLED was fabricated by spin-coating method. Applied electric field causes some effect on $SiO_2$ in PFO layer. Thus, interaction between polymers and affected $SiO_2$ might generate electrical and luminance properties change. Experimental results, show the reduced threshold voltage of 6 V(from 23 V to 17 V). The maximum current density was rather increased from $71A/m^2$ to $610A/m^2$ and maximum brightness was also increased from $7.19cd/m^2$ to $41.03cd/m^2$, 9 and 6 times each. Additionally we obtained colour broadening result due to the increasing of blue-green band emission. Consequently we observed that electrical and luminance properties are enhanced by adding $SiO_2$ and identified the possibility of controlling the emission colour of OLED device according to colour broadening.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.184-189
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• 2010

Organic light-emitting diodes (OLEDs) with single emissive layer structures using two fluorescent dopants were fabricated and the device was composed of ITO / NPB ($700{\AA}$) / MADN : C545T - 1.0% : DCJTB - 0.3% ($300{\AA}$) / Bphen ($300{\AA}$) / LiF ($10{\AA}$) /Al ($1,000{\AA}$). C545T and DCJTB were functioned as green fluorescent dye and red fluorescent dye under MADN as host material. Concentrations of C545T and DCJTB was changed in emissive layer of MADN. Optimized OLED device using two fluorescence dopants shows emission efficiency of 8.42 cd/A and luminescence of 3169 cd/$m^2$at 6 V with CIE color coordinate, (0.43, 0.50). Electroluminescence of optimized OLED showed two peak at 500 and 564 nm according to C545T and DCJTB. These results indicate that F$\ddot{o}$ster energy transfer energy transfer was from MADN to C545T and rather than to DCJTB continuously.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.540-542
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• 2008

By ETFOS software simulation to swiftly find out the shortcomings of the device structure and conserve the wastage of time cost in experiments, including the instruments deviations or human errors. Thereby we can calibrate the correct organic layer thickness by comparing the EL spectra with different NPB thicknesses.

• Vacuum Magazine
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• v.1 no.2
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• pp.24-29
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• 2014

Display is a key component in electronic devices. OLED is growing very fast recently due to the explosion of the smart phone market although still LCD is the dominating display technology in the display market at the moment. Also needs for the large area and high resolution TVs and flexible displays are increasing these days. Especially flexible display is expected to be one of the key technologies in mobile devices requiring small device size and large display size. Contrary to the conventional displays, flexible display requires organic materials for the substrate, the active driving element and also for the display element. Plastic film as a substrate, organic semiconductor as an active component of the transistor and organic light emitting materials or electronic paper as a display element are studied actively. In this article, mainly backplane technologies such as substrates and the transistor materials for flexible display will be introduced.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.755-759
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• 2005

This study was based on organic electroluminescence display. Especially, DPAVBi, AVBi and DPVBi for the emitting materials were synthesized by Wittig, Wittig-Horner reaction. This reaction was conducted between phosphorous ylide and 4-(diphenylamino)benzaldehyde, 9-anthraldehyde and benzophenone. The structural property of reaction products were analyzed by FT-IR, $^1H-NMR$ spectroscopy and thermal stability, reactivity and PL property were analyzed by melting point, yield and emission spectrum, respectvely. The photoluminescence spectra of a pure DPAVBi, AVBi and DPVBi were observed at approximately 445nm, 484nm and 450nm, respectively. In this study, it was known that DPAVBi, AVBi, DPVBi had a different reaction properties according to stability of ${\alpha}$-position carbonyl group of the aldehyde, ketone.

• Journal of Information Display
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• v.7 no.3
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• pp.13-18
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• 2006

Currently, the flexible organic light emitting devices (OLEDs) are investigated. They are very vulnerable to moisture, and thus have been found to show some problems. Thus, an effective barrier layer is needed to protect from moisture in air. We deposited thin films with magnesium oxide (MgO) and silicon oxide $(SiO_{2})$ compounds mixed at various mixture ratios on flexible polyether sulfone (PES) substrates by an electron-beam evaporator to investigate their applizability for transparent barrier applications. In this study, we found that as the MgO fraction increased, thin films comprised of MgO and $(SiO_{2})$ compounds became more amorphous and their surface morphologies become smoother and denser. In addition, zirconium oxide $(ZrO_{2})$ was added to the above-mentioned compound mixtures. $ZrO_{2}$ made thin mixture films more amorphous and made the surface morphology denser and more uniform. The water vapor transmission rates (WVTRs) of the whole films decreased rapidly. The best WVTR was obtained by depositing thin films of Mg-Si-Zr-O compound among the whole thin films. As the thin mixture films became more amorphous, and the surface morphology become denser and more uniform, the WVTRs decreased. Therefore, the thin mixture films became more suitable for flexible OLED applications as transparent passivation layers against moisture in air.

• Information Display
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• v.5 no.1
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• pp.25-30
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• 2004

Poly-Si TFT(Thin Film Transistor) technology are reviewed and discussed. Poly-Si TFTs fabricated on glass using low-temperature process were studied extensively for the application to LCD (Liquid Crystal Display) as well as to OLED(Organic Light Emitting Diode) Display. Currently, one of the application targets of the poly-Si TFT is emphasized on the highly functional SOG(System on Glass). Improvement of device characteristics such as an enhancement of carrier mobility has been studied intensively by enlarging the grain size. Reduction of the voltage and shrinkage of the device size are the trend of AM FPD(Active Matrix Flat Panel Display) as well as of Si LSI, which will arise a peculiar issue of uniformity for the device performance. Some approaches such as nucleation control of the grain seed or lateral grain growth have been tried, so far.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.980-983
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• 2002

We investigated the effect of quinolate metal complex layer as an electron injection layer on the performance of OLEDs and optimized the device efficiency by varying from 0.5 to 10nm thickness of Liq layer. OLED with a structure of indium tin oxide/$\alpha$-napthylphenylbiphenyl(NPB,40nm)/tris-(8-hydroxyquinoline)aluminum(Alq3, 50nm)/Aluminum(150nm) were fabricated in sequence. The device with 1nm Quinolate metal complex layer showed significant enhancement of the device performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.81-84
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• 2003

Conductive polyaniline(PANI)-camphosulfonic acid (CSA) film applied as a hole injection layer in ITO/PANI/P3HT/LiF/Al device. In the AFM images, electrochemically polymerized PANI-CSA films have the small particles and smooth sufficient for application as hole injection layer. By insertion of PANI-CSA buffer layer, the turn on voltage of ITO/PANI/P3HT/LiF/Al device lowed by 3V, whereas that of ITO/P3HT/LiF/Al device shows 5V.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.694-697
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• 2007

We demonstrate the use of screen printing in the fabrication of highly efficient phosphorescent polymer organic-light-emitting devices (OLEDs) based on a green-emitting $Ir(ppy)_3$ and a host polymer PVK. We incorporate PBD in the polymer host as an electron-transporting dopant and ${\alpha}-NPD$ as a hole transporting dopant. The best screen printed single-layer device exhibits very high peak luminous efficiency of 63 cd/A at a relatively high operating voltage of 17.1 V at the luminance of $650\;cd/m^2$. We observed the highest luminance of $21,000\;Cd/m^2$ at 35V. Due to the high operating voltage, despite of the high peak luminous efficiency the peak power efficiency was found to be 12.2 lm/W at the luminance of $470\;cd/m^2$ (15.9 V).