• Title/Summary/Keyword: Electroluminescence device

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Optical Characteristics and Electric Field Dependency of $Alq_3$ Thin Film (Alq3박막의 광학특성과 전계 의존성)

  • Lee, Cheong-Hak;Park, Dae-Hee
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1358-1360
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    • 1998
  • In this paper, organic thin film LED(light emitting diode) having ITO glass/$Alq_3$/Al structure using an $Alq_3$ was fabricated by the vacuum evaporation and the absorbance, wave length, 1-V characteristics were investigated. Electroluminescence of green and wavelength of 510[nm] were observed in this device. We observed absorbance form 320[nm] to 430[nm] and knew unstability of $Alq_3$ material as light emitting device.

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Synthesis and Electroluminescent Properties of Fluoranthene Derivatives

  • Kim, Soo-Kang;Park, Jong-Wook
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.621-624
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    • 2007
  • As a new fluoranthene derivative, a synthesis of benzo[k]fluoranthene was suggested, so new blue emitting materials, 7,12-diphenylbenzo[k] fluoranthene [DPBF] and 7,8,10- triphenylfluoranthene [TPF] were synthesized. $EL_{max}$ wavelength of the device using DPBF as an emitting layer was 436 and 454nm in the deepblue region, which are similar values with PL. The device that used DPBF as an emitting layer showed high efficiency of 2.11cd/A and the excellent color coordinate value of (0.161, 0.131) in deep-blue region.

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Syntheses of Improved Polymer/Organic Materials for Electroluminescence(EL) Device and Electro-Optical Characteristics(Ⅱ) Properties of EL Device using Squarylium Dye as Emitting Material (고기능 EL소자용 고분자/유기 재료의 합성 및 전기 광학적 특성(Ⅱ) Squarylium 색소를 이용한 EL소자의 특성)

  • Kim, Sung Hoon;Bae, Jin Seok;Hwang, Seok Hwan;Park, Lee Soon
    • Journal of the Korean Chemical Society
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    • v.41 no.3
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    • pp.144-149
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    • 1997
  • Organic electroluminescence devices(ELD) were fabricated using by molecularly doped method with N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) as a hole transport agent, squarylium dye as an emitting agent, and side chain liquid crystalline polymer(MCH) as matrix for TPD. An indium-tin-oxide(ITO) coated glass and an Mg electrode were used as the hole and the electron injecting electrode, respectively. The highest stability of ELD was obtained by spin coating method using dichloroethane as a solvent at a polymer/TPD concentration of 0.005 wt%. For the EL cell with ITO/polymer-TPD/SQ dye/Mg structure, we achieved light red luminescence at a current of 102 mA/$cm^2$ with an applied voltage of 23 V.

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A Study on the Enhancement of Emission Efficiency of an Organic EL Devices Using the RF Plasma (RF 플라즈마를 이용한 유기 EL소자의 발광 효율에 관한 연구)

  • 박상무;김형권;신백균;임경범;이덕출
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.9
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    • pp.400-406
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    • 2003
  • Efficient electrodes are devised for organic luminescent device(OLED). 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. In the case of device inserted the buffer layer by using the plasma polymerization 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 are made in the emitting layer. Therefore it realized the device capability of two times in the aspect of luminous efficiency than the device which do not be inserted the buffer layer. Experiments are limited to the device that has the structure of TPD/$AIq_3$, however, the aforementioned electrodes can similarly applied to the organic luminous device and the Polymer luminous device.

Optical Properties and Field Emission of ZnO Nanorods Grown on p-Type Porous Si

  • Park, Taehee;Park, Eunkyung;Ahn, Juwon;Lee, Jungwoo;Lee, Jongtaek;Lee, Sang-Hwa;Kim, Jae-Yong;Yi, Whikun
    • Bulletin of the Korean Chemical Society
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    • v.34 no.6
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    • pp.1779-1782
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    • 2013
  • N-type ZnO nanorods were grown on p-type porous silicon using a chemical bath deposition (CBD) method (p-n diode). The structure and geometry of the device were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) while the optoelectronic properties were investigated by UV/Vis absorption spectrometry as well as photoluminescence and electroluminescence measurements. The field emission (FE) properties of the device were also measured and its turn-on field and current at 6 $V/{\mu}m$ were determined. In principle, the growth of ZnO nanorods on porous siicon for optoelectronic applications is possible.

A Study on New Materials for Organic Active Devices (유기 능동 소자 제작을 위한 신소재 연구)

  • Lee, Sung-Jae;Lim, Sung-Taek;Shin, Dong-Myung;Choi, Jong-Sun;Lee, Hoo-Sung;Kim, Young-Kwan;Sohn, Byoung-Chung
    • Journal of the Korean Applied Science and Technology
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    • v.17 no.3
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    • pp.174-177
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    • 2000
  • The effect of a-sexithiophene(${\alpha}-6T$) layers on the light emitting diode (LED) were studied. The ${\alpha}-6T$ was used for a buffer layer in electroluminescent (EL) devices. Enhanced carrier (hole) injection and improved emission efficiency were observed. Carrier injection characteristics were investigated as a function of ${\alpha}-6T$ later thickness. The efficiency of the electroluminescence was proportional to the thickness of ${\alpha}-6T$ layer. The highest efficiency was observed 600A of ${\alpha}-6T$ later, which was about 1.5 times higher than that of device without ${\alpha}-6T$ later. The device with a-6T showed an operation voltage lowered by 2V. The ${\alpha}-6T$ layer can substitute hole blocking layer, and control charge injection properties.

White Electroluminescence from Bicarbazyl-containing Conjugated Polymers as Single-Emitting Component

  • Kang, In-Nam;Kim, Yang-Bae;Lim, Sung-Hwan;Chung, Min-Chul;Oh, Se-Young;Kim, Sung-Ryong;Lee, Ji-Hoon
    • Bulletin of the Korean Chemical Society
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    • v.29 no.1
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    • pp.135-138
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    • 2008
  • Two bicarbazyl-containing fluorene copolymers, PFEBCz (95/5) and PFEBCz (75/25), were synthesized for white light electroluminescence from a single emitting polymer. All synthesized polymers were soluble in common organic solvents such as chloroform and toluene. The weight-average molecular weights (Mw) of the PFEBCz (95/5) and PFEBCz (75/25) copolymers were found to be 11,000 and 5,700 with polydispersity indices 1.4 and 1.8. The EL spectrum of the PFEBCz (75/25) device showed bright white-light emission with CIE coordinates of (0.32, 0.34) at 1000 cd/m2, which is very close to that for pure white (0.33, 0.33). This white emission may have been due to strong excimer formation between the bicarbazyl and fluorene polymer backbone. The device exhibited a maximum brightness of 3400 cd/m2 with a maximum efficiency of 0.2 cd/A.

Effect of Microstructure of Quantum Dot Layer on Electroluminescent Properties of Quantum Dot Light Emitting Devices (양자점 층의 미세구조 형상이 양자점 LED 전계 발광 특성에 미치는 효과)

  • Yoon, Sung-Lyong;Jeon, Minhyon;Lee, Jeon-Kook
    • Korean Journal of Materials Research
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    • v.23 no.8
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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.

A Study on the Green Eemission Ccharacteristics of $Alq_3$ ($Alq_3$의 녹색발광특성에 관한 연구)

  • Kang, Young-Chol;Chon, Dong-Kyu;Song, Jin-Won;Kim, Young-Keun;Kim, Ju-Seung;Gu, Hal-Bon;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.957-960
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    • 2002
  • Electroluminescence(EL) from conjugated polymers has recently received great attention because polymer light-emitting diodes(LEDs) clealy have potential for applications such as large-area displays. The operation of polymer LEDs is based on double injection of electrons and holes from the elextrodes, followed by formation of excitons whose radiative decay results in light emission at wavelength characteristic to the material. In this paper, we fabricated the single layer EL device using $Alq_3$ as emitting material. According as turn on voltage could know about 5.5V in voltage-current characteristics and voltage rise, current could see that increase as non-linear. Current and ruminance can see that express similar relativity in voltage, and could know that ruminance is expressing current relativity.

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Electroluminescence and Electronic properties of multi1ayer organic Thin Film (다층구조를 갖는 유기박막의 발광 및 전자물성)

  • Lee, Cheong-Hak;Kim, Jeong-Tae;Park, Bok-Kee;Park, Dae-Hee
    • Proceedings of the KIEE Conference
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    • 1998.11c
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    • pp.792-794
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    • 1998
  • The TPD and the $Alq_3$ film are widely used as a hole transport layer and an emitter layer respectively, in organic electroluminescent(EL) device (ITO Glass/TPD/$Alq_3$/metal). In this structure, we fabricated two models. Model(1) having ITO glass/$Alq_3$/Al structure and model(2) having ITO Glass/TPD/$Alq_3$/Al structure were fabricated by the vacuum evaporation. The comparison between model(1) and model(2) was made about the absorbance, the wave length, the current-voltage characteristic and the ln I - $V^{(1/2)}$characteristic respectively. Electroluminescence of green and wavelength of 510[nm] were observed in both model. We observed absorbance from 320[nm] to 430[nm] in $Alq_3$ material and from 250[nm] to 400[nm] in TPD material.

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