• Journal of Information Display
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• 제2권2호
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• pp.45-51
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• 2001

Four types of conjugated polymers, poly(MEHPV-PV), poly(MEHPV-BPV), poly(MEHPV-AV) and poly(PZV-AV) were synthesized by Homer-Emmons reaction using potassium tert-butoxide. The Homer-Emmons reaction gave electroluminescent(EL) copolymers in good yield. Of the EL copolymers synthesized, poly(PZV-AV) containing phenothiazinylene vinylene and anthrylene vinylene as repeat unit exhibited red color in the light emitting diode(LED) which was very close to the NTSC standard red. Besides, double layer LED made with $Alq_3$ electron transport layer exhibited both enhanced emission intensity and efficiency compared to the single layer LED.

• 한국재료학회지
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• 제13권8호
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• pp.514-518
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• 2003

As a fundamental study on organic electroluminescence(EL), blue emitting materials were synthesized and characterized. Individual blue colored hydrazone derivatives were synthesized from the reaction of aldehydes (phthalaldehyde, isophthalaldehyde) with the corresponding amnios (1-methyl -1-phenylhydrazine, 1,1-diphenylhydrazine hydrochloride). Recrystallization of hydrazones from chloroform revealed the melting temperature within $142∼156^{\circ}C$. Photoluminescence(PL) analysis on each hydrazone showed that emission range were blue(458∼478 nm). The structure of obtained hydrazones were elucidated by FT-IR, $^1$H-NMR and C, H, N elemental analyzer.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.755-760
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• 2008

영상 Display의 시장 동향과 기술 동향에 대하여 기술하였다. 영상 Display 로서는 그밖에 유기 EL(Electroluminescence), FED(Filed Emission Display) 등이 있고 차세대 Display도 개발이 진행되고 있다. 양자 모두 스스로 발광하는 형태를 취하기 위해서는 Back Light가 필요하지 않고, 박형과, 넓은 시야각, 또한 응답 속도가 빠르고 때문에 액정 Display 보다 유리하리라 판단된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.62-62
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• 1999

• Journal of Information Display
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• 제2권3호
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• pp.1-5
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• 2001

The effect of doping on the energy transfer and charge carrier trapping processes has been studied in organic light-emitting diodes (OLEDs) doped with a fluorescent laser dye. The devices consisted of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1-biphenyl-4,4'-diamine (TPD) as a hole transporting layer, tris(8-hydroxyquinoline) aluminum ($Alq_3$) as the host, and a fluorescent dye, 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1 H,5H-benzo[i,j]quinolizin-8-yl) vinyl]-4H-pyran) (DCM2) as the dopant. Temperature dependence of the current-voltage-luminescence (I-V-L) characteristics, the electroluminescence (EL) and photoluminescence (PL) spectra are studied in the temperature ranging between 15 K and 300 K. The emission from DCM2 was seen to be much stronger compared with the emission from $Alq_3$, indicative of efficient energy transfer from $Alq_3$ to DCM2. In addition, the EL emission from DCM2 increasd with increasing temperature while the emission from the host $Alq_3$ decreased. The result indicates that direct charge carrier trapping becomes efficient with increasing temperature. The EL emission from DCM2 shows a slightly sublinear dependence on the current density, implying the enhanced quenching of excitons at high current densities due to the exciton-exciton annihilation.

• Journal of Information Display
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• 제5권4호
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• pp.12-17
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• 2004

A series of statistical random copolymers of dioctylfluorene (DOF) and 3,4-ethylenedioxythiophene (EDOT) were synthesized by Ni (0) mediated polymerization and their light-emitting properties were compared with poly (9,9-di-n-octylfluorene) (PDOF). The synthesized polymers were characterized using UV-vis spectroscopy, TGA, photoluminescence (PL) & electroluminescence (EL) spectroscopy and by conducting molecular weight studies. The resulting polymers were found to be thermally stable and readily soluble in organic solvents. The UV-visible absorption and PL emission spectra of the copolymers were gradually red-shifted as the fraction of EDOT in copolymers increased. Light-emitting devices were fabricated in an ITO (indium-tin oxide)/PEDOT/polymer/Ca/Al configuration. Interestingly, the EL spectra of these devices were similar to the PL spectra of the corresponding polymer film. However, the EL devices constructed from the copolymer showed more than 10 times higher efficiency level than the devices constructed from the PDOF homopolymer. This higher efficiency is possibly the result of better charge carrier balance in the copolymer systems due to the lower HOMO levels of the copolymers in comparison to that of PDOF homopolymer.

• 한국전기전자재료학회논문지
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• 제19권6호
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• pp.568-573
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• 2006

We have synthesized new blue light emitting random copolymers, poly(9,9'-n-dioctylfluorene-co-perfluorobenzene-1,4-diyl)s (PFFBs), via Ni(0)-mediated coupling reactions. The weight-average molecular weights ($M_w$) of the PFFB copolymers ranged from 9,000 to 15,000. The PFFB copolymers dissolved in common organic solvents such as THF and toluene. The PL emission peaks of the PFFB copolymers were at around 420, 440, and 470 nm. EL devices were fabricated in ITO/PEDOT/polymer/Ca/Al configurations using these polymers. These EL devices were found to exhibit pure blue emission with approximate CIE coordinates of (0.15, 0.11) at $100cd/m^2$. The blue emissions of these devices might be due to the restriction of the polymer chains to aggregation by introducing of the highly electronegative fluorine moieties. The maximum brightnesses of the PFFB copolymer devices ranged from 140 to $3600cd/m^2$ with maximum efficiencies from 0.2 to 0.6 cd/A. The enhanced efficiency of the PFFB (8/2) copolymer device results from the inhibition of excimer formation by the introduction of the electronegative fluorine moieties into the copolymers.

• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.1043-1047
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• 2006

New electroluminescence polymer, poly(5,10-dihexyl-5,10-dihydroindolo[3,2-b]indole-2,7-diyl) (PININO) was synthesized by Yamamoto conditions with Ni(0) catalyst. The full characterization of structures and properties as well as the performances of the electroluminescence devices of the new polymer are presented. The resulting polymer, which exhibits good solubility in common organic solvents, was used as the electroluminescence layer for the light-emitting diodes (LEDs) (ITO/PEDOT/polymer/Al). PININO shows turn-on voltage of 2.5 V, and electroluminescence (EL) with maximum peak at 490 nm, maximum brightness of 40 cd/$m^{2}$ at 8 V, and efficiency of 0.002 cd/A at 350 mA/$cm^{2}$.

• 대한화학회지
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• 제48권4호
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• pp.371-378
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• 2004

기존의 $SrGa_2S_4:Eu^{2+}$ 녹색 발광 형광체는 주로 CRT (Cathode Ray Tube)용이나 FED (Field Emission Display), 그리고 EL (Electroluminescence)용 발광소자로 많이 연구되어졌다. 현재는 장파장 영역의 여기 특성을 이용한 LED (Light Emitting Diode)용 형광체로 주목 되어지고 있다. $SrGa_2S_4:Eu^{2+}$ 형광체의 일반적 합성 방법은 Flux를 이용하여 인체에 유해한 $H_2S$나 $CS_2$ 기체를 사용할 뿐만 아니라 높은 합성온도, 긴 반응시간 및 공정이 복잡한 단점을 지니고 있다. 따라서 본 실험은 황화물계 원료인 SrS, $Ga_2S_3$ 그리고 EuS를 출발 물질로 하여 $H_2S$ 기체를 사용하지 않고 혼합 기체$(5% H_2/95% N_2)$를 사용해 환원 분위기 하에서 $SrGa_2S_4:Eu^{2+}$을 합성하였다. 그리고 다양한 합성 조건과 LED용으로 사용되기 위해 수세처리와 Sieving 과정을 거친 형광체의 발광특성을 검토하였다.

• 한국재료학회지
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• 제23권8호
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• pp.430-434
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• 2013

Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick $ZnSnO_x$ with a resistivity of $10{\Omega}{\cdot}cm$, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.