• 제목/요약/키워드: Emitting

검색결과 3,863건 처리시간 0.035초

CaxSr2-xSiO4:Eu2+ Green-emitting Nano Phosphor for Ultraviolet Light Emitting Diodes

  • Kim, Jong Min;Choi, Hyung Wook
    • Transactions on Electrical and Electronic Materials
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    • 제15권5호
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    • pp.249-252
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    • 2014
  • The aim of this work is to investigate the effect of $Ca_xSr_{2-x}$ and activator on the structural and luminescent properties of green-emitting $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ nano phosphor. Using urea as fuel and ammonium nitrate as oxidizer, $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ has been successfully synthesized, using a combustion method. The particles were found to be small, spherical and of round surface. SEM imagery showed that the phosphors particles are of nanosize. The $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ emission spectrum for 360 nm excitation showed a single band, with a peak at 490 nm, which is a green emission. The highest luminous intensity was at $1,000^{\circ}C$, which was obtained when the $Eu^{2+}$ content (y) was 0.05. The results support the application of $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor as a fluorescent material for ultraviolet light-emitting diodes (UV-LEDs). Characteristics of the synthesized $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and photoluminescence (PL) detection.

전달 행렬 방법을 이용한 850 nm수직 공진기 레이저 구조의 최적설계 (Design of 850 nm Vertical-Cavity Surface-Emitting Lasers by Using a Transfer Matrix Method)

  • 김태용;김상배
    • 대한전자공학회논문지SD
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    • 제41권1호
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    • pp.35-46
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    • 2004
  • Vertical-Cavity Surface-Emitting Laser(VCSEL)는 짧은 공진기(cavity)와 여러 층의 distributed Bragg reflector(DBR)층을 거울로 사용하기 때문에, edge-emitting lasers(EELs)와는 달리, 광출력 및 변환효율 등의 예측이 쉽지 않다. 그 주된 원인은 VCSEL에서는 Fabry-Perot 레이저와는 달리, 각각의 DBR 거울 층들이 손실을 가지고 있기 때문으로 이에 따라 상/하향광출력 비나 변환효율을 계산해 내는 데에 어려움이 있다. 그러나 전달 행렬 방법(transfer matrix method, TMM)을 이용하면, VCSEL과 같은 여러 층을 갖는 구조에서의 성능 지수를 정확히 계산할 수 있다. 이 논문에서는 전달 행렬 방법을 이용하여 VCSEL의 구조 변화에 따른 문턱이득, 문턱전류 밀도 및 변환효율을 구하였으며 문턱전류 및 변환효율 모두를 고려한 VCSEL의 최적 구조 설계 기법을 제시하였다.

The Investigation of Photolithographic Patterning Method for Polymer Light Emitting Diodes

  • Kim, Mi-Kyung;Lee, Jeong-Ik;Kim, Duck-Il;Oh, Ji-Young;Hwang, Chi-Sun;KoPark, Sang-He;Yang, Yong-Suk;Chu, Hye-Yong;Kim, Suk-Kyung;Hwang, Do-Hoon;Lee, Hyung-Jong
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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    • pp.592-594
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    • 2004
  • We have investigated the photolithographic patterning method of light emitting polymer film for polymer light emitting diodes (PLEDs). Blue light emitting polymers based on polyfluorene, which can be cured photochemically to yield an insoluble form, have been synthesized using Ni(0) mediated Yamamoto polymerization. The relationship between patterning property and several variables such as the intensity of the exposed UV light, the concentrations of additives, has been studied by using optical microscope analysis, UV/visible spectroscopy, and photoluminescence. We have successfully fabricated PLEDs composed of the patterned emissive layer and their electroluminescence property has been also investigated. In this presentation, the detailed photolithographic patterning method and its application for polymer light emitting display will be discussed.

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HALOGEN LIGHT CURING UNIT 과 LIGHT EMITTING DIODES CURING UNIT 을 이용하여 중합되어진 복합레진의 마모 특성 비교 (Wear Of Resin Composites Polymerized By Conventional Halogen Light Curing And Light Emitting Diodes Curing Units)

  • 이권용;김환;박성호;정일영;전승범
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.1057-1060
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    • 2004
  • In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15 N contact force in a reciprocal sliding motion with sliding distance of 10 mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP > Surefil > Compoglass > Z100 > Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed the least wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as a curing unit for composite resin restorations.

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White organic light-emitting devices with a new DCM derivative as an efficient red-emitting material

  • Lee, Mun-Jae;Lee, Nam-Heon;Song, Jun-Ho;Park, Kyung-Min;Yoo, In-Sun;Lee, Chang-Hee;Hwang, Do-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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    • pp.940-943
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    • 2003
  • We report the fabrication and the characterization of white organic light-emitting devices consisting of a red-emitting layer of a new DCM derivative doped into 4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (${\alpha}-NPD$) and a blue-emitting layer of 1,4-bis(2,2-diphenyl vinyl)benzene (DPVBi). The device structure is ITO/PEDOT:PSS/${\alpha}-NPD$ (50 nm)/${\alpha}-NPD$:DCM (5 nm, 0.2 %)/DPVBi (x)/Alq3 (40 nm)/LiF (0.5 nm)/Al. The electroluminescence (EL) spectra consist of two broad peaks around 470 nm and 580 nm with the spectral emission depending on the thickness of DPVBi. The device with the DPVBi thickness of about 20 nm show a white light-emission with the Commission Internationale d'Eclairage(CIE) chromaticity coordinates of (0.33, 0.36). The external quantum efficiency is 2.6% and luminous efficiency is 2.0 lm/W at a luminance of 100 $cd/m^{2}$. The maximum luminance is about 30,270 $cd/m^{2}$ at 13.9 V.

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$Alq_3$에 기초한 유기 발광 소자에서 전기전도특성과 등가회로분석 (Electrical Conduction Mechanism and Equivalent Circuit Analysis in $Alq_3$ based Organic Light Emitting Diode)

  • 정동회;신철기;이동규;이준웅;이석재;이원재;장경욱;김태완
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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    • pp.103-106
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    • 2004
  • We have studied a conduction mechanism and equivalent circuit analysis in $Alq_3$ based Organic Light Emitting Diode. The conduction mechanism in organic light emitting diode can be classified into three regions; ohmic region, space-charge-limited current (SCLC) region and trap-charge-limited current (TCLC) region depending on the region of applied voltage. Equivalent circuit model of organic light emitting diode can be established using a parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance $R_s$.

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유기 전기 발광 소자에서 $\alpha$-septithiophene을 이용한 buffer layer의 영향 (The effects of buffer layer using $\alpha$-septithiophene on the organic light emitting diode)

  • 이기욱;임성택;신동명;박종욱;박호철
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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    • pp.53-56
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    • 2002
  • The effect of $\alpha$-septithiophene (${\alpha}-7T$) layers on the organic light emitting diode(OLED) was studied. The ${\alpha}-7T$ was used for a buffer layer in OLED. Hole injection was investigated and improved emission efficiency. The OLEDs structure can be described as indium tin oxide(ITO)/ buffer layer / hole transporting layer / emitting layer / electron transporting layer / LiF / Al. The hole transporting layer were composed of N,N-diphenyl-N,N-di(3-methylphenyl)-1,1-biphenyl-4,4-diamine(TPD), and N,N-di(naphthalene-1-ly)-N,N-diphenyl-benzidine( ${\alpha}$-NPD). The emitting layer, and electron transporting layer consist of tris(8-hydroxyquinolinato) aluminum($Alq_3$). All organic layer were deposited at a background pressure of less than $10^{-6}$ torr using ultra high vacuum (UHV) system. The ${\alpha}-7T$ layer can substitute the hole blocking layer, and improve hole injection properties.

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Efficient Blue Light Emitting Diode by Using Anthracene Derivative with 3,5-Diphenylphenyl Wings at 9- and 10-Position

  • Kim, Yun-Hi;Lee, Sung-Joong;Jung, Sang-Yun;Byeon, Ki-Nam;Kim, Jeong-Sik;Shin, Sung-Chul;Kwon, Soon-Ki
    • Bulletin of the Korean Chemical Society
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    • 제28권3호
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    • pp.443-446
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    • 2007
  • The novel blue light emitting material, 9,10-bis(3',5'-diphenylphenyl)anthracene (BDA) was synthesized by Suzuki coupling reaction and characterized by the measurements of 1H NMR, 13C NMR and FT-IR. The new anthracene derivative, which contains anthracene as a main core unit and 3',5'-diphenylphenyl group derivative as wings, has high fluorescence yield, good thermal stability, and high glass transition temperature at 188 oC. With the newly non-doped blue emitting material in the multilayer device structure, it was possible to achieve the current efficiency of 3.0 cd/A. The EL spectrum of the ITO/CuPc/α-NPD/BDA/Alq3/LiF/Al device showed a maximum wavelength (λmax) at 440 nm. The emitting color of device showed the blue emission (x,y) = (0.18,0.19) at 10 mA/cm2 in CIE (Commission Internationale de l'Eclairage) chromaticity coordinates.

Dependence of Light-Emitting Characteristics of Blue Phosphorescent Organic Light-Emitting Diodes on Electron Injection and Transport Materials

  • Lee, Jeong-Ik;Lee, Jonghee;Lee, Joo-Won;Cho, Doo-Hee;Shin, Jin-Wook;Han, Jun-Han;Chu, Hye Yong
    • ETRI Journal
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    • 제34권5호
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    • pp.690-695
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    • 2012
  • We investigate the light-emitting performances of blue phosphorescent organic light-emitting diodes (PHOLEDs) with three different electron injection and transport materials, that is, bathocuproine(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) (Bphen), 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (Tm3PyPB), and 2,6-bis(3-(carbazol-9-yl)phenyl)pyridine (26DCzPPy), which are partially doped with cesium metal. We find that the device characteristics are very dependent on the nature of the introduced electron injection layer (EIL) and electron transporting layer (ETL). When the appropriate EIL and ETL are combined, the peak external quantum efficiency and peak power efficiency improve up to 20.7% and 45.6 lm/W, respectively. Moreover, this blue PHOLED even maintains high external quantum efficiency of 19.6% and 16.9% at a luminance of $1,000cd/m^2$ and $10,000cd/m^2$, respectively.

LB법에 의한 제막된 poly(3-hexylthiophene)의 발광특성 (Emitting Properties of Poly(3-hexylthiophene) deposited by LB method)

  • 서부완;김주승;구할본;이경섭;박복기;박계춘
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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    • pp.962-964
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    • 1999
  • We studied emitting properties of devices fabricated using the spin-coating and Langmuir-Blodgett[LB] technique. The LB technique has the advantage of precise control of the thickness better than spin-coating method. Poly(3-hexylthiophene)[P3HT] LB films used as the emitting layer in light-emitting devices. LB monolayers were deposited 27 layers onto the indium-tin-oxide[ITO] as Y-type films by the vertical dipping method. The thickness is about 80nm. Absorption spectrum of LB films presented that P3HT is regiorandom conformation. Also, current-voltage-luminance characteristics and electroluminescence spectra of light-emitting devices fabricated by LB method is studied. In current-voltage-luminescence characteristics, turn-on voltage of P3HT LB film LEDs is higher than that of spin-coating LEDs. But electroluminescence spectrum is similar to the spin-coating LEDs. The orange-red light was clearly visible in a darkened room.

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