• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.379-382
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• 2004

In this paper we fabricated a test panel for AMOLED on glass and PET substrate. The test panel consisted of the various size of OTFTs and OLEDs and the current driving capability of OTFTs for OLEDs has been investigated. OTFTs were made of the inverted staggered structure and employed polyvinylphenol (PVP) as the gate insulator and pentacene thin film as the active layer. The OTFTs produced the filed effect mobility of $0.3 cm^2/V.sec$ and on/off current ratio of $10^5$. OLEDs consisted of TPD for HTL and Alq3 for EML with 35nm thick, generating green monochrome light. We found that OTFT with channel length of 70${\mu}m$ and channel width of over 3.5mm provided the sufficient current to OLED to generate the luminescence of $0.3Cd/m^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1034-1037
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• 2004

In this paper we fabricated a test panel for AMOLED on glass and PET substrate. The test panel consisted of the various size of OTFTs and OLEDs and the current driving capability of OTFTs for OLEDs has been investigated. OTFTs were made of the inverted staggered structure and employed polyvinylphenol (PVP) as the gate insulator and pentacene thin film as the active layer. The OTFTs produced the filed effect mobility of 0.3$cm^2$/V.sec and on/off current ratio of $10^5$. OLEDs consisted of TPD for HTL and Alq3 for EML with 35nm thick, generating green monochrome light. We found that OTFT with channel length of 70${\mu}m$and channel width of over 3.5mm provided the sufficient current to OLED to generate the luminescence of 0.3Cd/$m^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1429-1432
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• 2007

We fabricated white organic light emitting diodes(WOLED) having two complementary and three primary colors with emission layers of DPVBi / MADN : DCM2-0.5% and DPVBi / $Alq_3$ / MADN : DCM2-1.5%, respectively. WOLED using three primary colors shows broad electroluminescence including green emission peak at 510nm while optical properties of the two complementary WOLED was higher current efficiency of 6.2 cd/A than 4.9 cd/A of three primary color WOLED. The maximum luminescence of WOLED with two complimentary color was $15200cd/m^2$ along with luminous efficiency 6.2cd/A, as achieving stable white color coordinates for both of WOLEDs at (0.33 , 0.33) almost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.641-646
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• 2005

To fabricate a single layer white organic light emitting diode (OLED), a novel non-conjugated blue emitting material PPPMA-co-DTPM copolymer was synthesized containing a perylene moiety unit with hole transporting and blue emitting ability and a triazine moiety unit with electron transporting ability. The devices were fabricated using PPPMA-co-DTPM $(PPPMA[70\;wt\%]:DTPM[30\;wt\%])$ copolymer by varying the doping concentrations of each red, green and blue fluorescent dye, by molecular-dispersing into Toluene solvent with spin coating method. In case of ITO/PPPMA-co-DTPM:TPB$(3\;mol\%):C6(0.04\;mol\%):NR(0.015\;mol\%)/Al$ structure, as they were molecular-dispersing into 30 mg/ml Toluene solvent, nearly-pure white light was obtained both (0.325, 0.339) in the CIE coordinates at 18 V and (0.335, 0.345) at 15 V. The turn-on voltage was 3 V, the light-emitting turn-on voltage was 4 V, and the maximum external quantum efficiency was $0.667\%$ at 24.5 V. Also, in case of using 40 mg/ml Toluene solvent, the CIE coordinate was (0.345, 0.342) at 20 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.313-314
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• 2005

Organic light emitting diodes(OLEDs) are widely used as one of the information display techniques. We synthesized (1,10-phenanthroline)- (8-hydroxyquinoline) [Zn(Phen)q]. We studied the improvement of OLEDs properties using Zn(phen)q. The Ionization Potential(IP) and the Electron Affinity(EA) of Zn(phen)q investigated using cyclic voltammetry(CV). The IP, EA and Eg were 7.leV, 3.4eV and 3.7eV, respectively. The PL spectrum of Zn(phen)q was yellowish green as the wavelength of 535nm. In this study, we used Zn(phen)q as electron transporting layer(ETL) inserted between emitting layer(EML) and cathode. As a result, Zn(phen)q is useful as electron transporting layer to enhance the performance of OLEDs.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1569-1574
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• 2005

To develop new hole-blocking materials for phosphorescent organic light-emitting diodes (PhOLEDs), 5,6-dihydro-2,9-diisopropyl-4,7-diphenyl[1,10]phenanthroline (1) and 5,6-dihydro-2,9-diisopropyl-4-(4-methoxyphenyl)-7-phenyl[1,10]phenanthroline (2) were synthesized. While the absorption spectrum of 1 is very similar to that of 2, the photoluminescence spectrum of 1 has the feature of the narrower and blue-shifted blueviolet emission at the peak of 356 nm compared to that of 2. The HOMO and LUMO energy levels of 1 and 2 were estimated from the measurement of cyclic voltammetry, and 1 has the appropriate levels for a holeblocking layer (HBL). The use of 1 as a HBL in a green PhOLED led to good efficiency of 23.6 cd/A at 4.4 mA/$cm^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.514-516
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• 2003

We have fabricated an air stable blue emitting organic electroluminescent devices (OLEDs) with a carbazole based emitting molecule, Bis(3-N-ethylcarbazolyl)terephthalidene (BECP). Our device emits strong blue at 472 nm with the luminance efficiency of near 1 lm/W at a voltage and current density of 8 V and 5.7 mA/cm2, respectively, reaching the brightness up to 5000 cd/m2 at 270 mA/cm2. Finally, in order to tune the emission color from blue to green, we have used Bis(3-N-ethylcarbazolyl)cynoterephthalidene (BECCP), a derivative of BECP by adding cyno group in side chain, and compared the electroluminscence (EL) of OLEDS prepared by BECCP to that of BECP based OLEDs.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.347-351
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• 2008

We have fabricated and evaluated newNew high high-efficiency green green-light light-emitting phosphorescent devices with an emission layer of [$TCTA/TCTA_{1/3}TAZ_{2/3}/TAZ$] : $Ir(ppy)_3$ were fabricated and evaluated, and compared the electroluminescence characteristics of these devices were compared with the conventional phosphorescent devices with emission layers of ($TCTA_{1/3}TAZ_{2/3}$) : $Ir(ppy)_3$ and (TCTA/TAZ) : $Ir(ppy)_3$. The current density, luminance, and current efficiency of the a device with an emission layer of ($80{\AA}-TCTA/90^{\circ}{\AA}-TCTA_{1/3}TAZ_{2/3}/130{\AA}-TAZ$) : 10%-$Ir(ppy)_3$ were $95\;mA/cm^2$, $25000\;cd/m^2$, and 27 cd/A at an applied voltage of 10 V, respectively. The maximum current efficiency was 52 cd/A under the a luminance value of $400\;cd/m^2$. The peak wavelength and FWHM (FWHM (full width at half maximum) in the electroluminescence spectral were 513 nm and 65 nm, respectively. The color coordinate was (0.30, 0.62) on the CIE (Commission Internationale de I'Eclairage) chart. Under the a luminance of $15000\;cd/m^2$, the current efficiency of the a device with an emission layer of ($80{\AA}-TCTA/90{\AA}-TCTA_{1/3}TAZ_{2/3}/130{\AA}-TAZ$) : 10%-$Ir(ppy)_3$ was 34 cd/A, which has beenshowed an improvement of improved 1.7 and 1.4 times compared to those of the devices with emission layers of ($300{\AA}-TCTA_{1/3}TAZ_{2/3}$) : 10%-$Ir(ppy)_3$ and ($100{\AA}-TCTA/200{\AA}$-TAZ) : 10%-$Ir(ppy)_3$, respectively.

• Journal of the Korean Graphic Arts Communication Society
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• v.22 no.2
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• pp.179-198
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• 2004

Organic electroluminescent devices are light-emitting diodes in which the active materials consist entirely of organic materials. Recently, many fluorescent organic materials have been reported and the study on synthesis and application of new organic light-emitting materials has been demanded. This paper reports the optical and electrical characteristics of OLEDs using novel polymers containing biphenyl structure. First, Optical properties of novel light-emitting biphenyl derivatives doped with poly(9-vinyl carbazole)(PVK) and emitted blue, bluish green color, which is attributed to the overlap area between PL spectrum of host(PVK) and absorption spectra of guests(polymer). This is correspondent with F$\"{o}$rster energy transfer process in the blends. And, OLED devices were fabricated using poly (3,4-ethylenedioxy thiophene) (PEDOT) as a hole injection material and tris-(8-hydroxyquinoline) aluminum ($Alq_3$) as an electron transporting material. EL devices fabricated as ITO/PEDOT/PVK doped with biphenyl derivatives/$Alq_3$/Li:Al and I-V-L chatacteristics and emitting efficiency of EL devices were examined. Finally, the drift mobility of PVK doped with biphenyl derivatives and $Alq_3$ were measured by TOF technique varying applied electric field. EL efficiency was increased as the ratio of hole mobility of PVK doped with biphenyl derivatives and electron mobility of $Alq_3$ was close to one.

• Korean Journal of Materials Research
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• v.21 no.4
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• pp.212-215
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• 2011

New organic light-emitting diodes with structure of indium-tin-oxide[ITO]/N,N'-diphenyl-N, N'-bis-[4-(phenyl-m-tolvlamino)-phenyl]-biphenyl-4,4'-diamine[DNTPD]/1,1-bis-(di-4-poly-aminophenyl) cyclohexane[TAPC]/bis(10-hydroxy-benzo(h)quinolinato)beryllium[Bebq2]/Bebq2:iridium(III)bis(2-phenylquinoline-N,C2')acetylacetonate[(pq)2Ir(acac)]/ET-137[electron transport material from SFC Co]/LiF/Al using the selective doping of 5%-(pq)2Ir(acac) in a single Bebq2 host in the two wavelength (green, orange) emitter formation were proposed and characterized. In the experiments, with a 300${\AA}$-thick undoped emitter of Bebq2, two kinds of devices with the doped emitter thicknesses of 20${\AA}$ and 40${\AA}$ in the Bebq2:(pq)2Ir(acac) were fabricated. The device with a 20${\AA}$-thick doped emitter is referred to as "D-1" and the device with a 4${\AA}$-thick doped emitter is referred to as "D-2". Under an applied voltage of 9V, the luminance of D-1 and D-2 were 7780 $cd/m^2$ and 6620 $cd/m^2$, respectively. The electroluminescent spectrum of each fabricated device showed peak emissions at the same two wavelengths: 508 nm and 596 nm. However, the relative intensity of 596 nm to 508 nm at those wavelengths was higher in the D-2 than in the D-1. The D-1 and D-2 devices showed maximum current efficiencies of 5.2 cd/A and 6.0 cd/A, and color coordinates of (0.31, 0.50) and (0.37, 0.48) on the Commission Internationale de I'Eclairage[CIE] chart, respectively.