• Title, Summary, Keyword: Organic light-emitting diodes

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Performance Analysis of Layered and Blended Organic Light-Emitting Diodes

  • Park, Jong-Woon;Yim, Yeon-Chan;Heo, Gi-Seok;Kim, Tae-Won;Lee, Jong-Ho;Park, Seung-Hwan
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.424-427
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    • 2008
  • We make performance simulations of three different organic light-emitting diodes (OLEDs), one of which is based on a conventional layered structure and the others on a blended structure where an emitting layer (EML) is either uniformly or stepwise mixed with an electron transport layer (ETL), Tris-(8-hydroxyquinoline) aluminum ($Alq_3$).

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Bipolar type indolocarbazole host for green phosphorescent organic light-emitting diodes

  • Im, Yirang;Han, Si Hyun;Lee, Jun Yeob
    • Journal of Industrial and Engineering Chemistry
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    • v.66
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    • pp.381-386
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    • 2018
  • A bipolar host designed using indolocarbazole as a bipolar moiety was developed by coupling two indolocarbazole moieties via a phenyl linker. The indolocarbazole derived hosts could carry holes and electrons in the emitting layer, functioning as bipolar hosts in the green phosphorescent organic light-emitting diodes. The linker based molecular design was superior to the directly coupled molecular design to match carrier balance for high quantum efficiency in the green phosphorescent devices.

Current-Voltage Characteristics with a direction of Voltage in Organic Light-Emitting Diodes (유기 전기발광 소자에서 인가전압 방향에 따른 전류-전압 특성)

  • Kim, Sang-Keol;Chung, Dong-Hoe;Chung, Taek-Gyun;Lee, Ho-Sik;Kim, Tae-Wan;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.130-132
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    • 2001
  • We have investigated current-voltage (I-V) characteristics of organic light-emitting diodes based on $TPD/Alq_3$ organics depending on the application of forward-reverse bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the I-V characteristics were measured. We have observed that the I-V characteristics shows a current mxima at low voltage, which is possibly not related to the emission from $Alq_3$.

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Current-Voltage Characteristics with a direction of Voyage in Organic Light-Emitting Diodes (유기 전기발광 소자에서 인가전압 방향에 따른 전류-전압 특성)

  • 김상걸;정동회;정택균;이호식;김태완;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.130-132
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    • 2001
  • We have investigated current-voltage(I-V) characteristics of organic light-emitting diodes based on TPD/Alq$_3$ organics depending on the application of forward-reverse bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the I-V characteristics were measured. We have observed that the I-V characteristics shows a current mxima at low voltage, which is possibly not related to the emission from Alq$_3$.

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Equivalent-Circuit Analysis of Organic Light-Emitting Diodes in $ITO/TPD/Alq_3/Al$ ($ITO/TPD/Alq_3/Al$ 유기발광소자의 등가회로 분석)

  • Ahn, Joon-Ho;Oh, Yong-Chul;Hong, Jin-Woong;Lee, Joon-Ung;Song, Min-Jong;Kim, Tae-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.188-191
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    • 2004
  • We have investigated equivalent-circuit analysis of organic light-emitting diodes in $ITO/TPD/Alq_3/Al$. Complex impedance Z of the device was measured in the frequency range of $40Hz{\sim}1MHz$. We are able to interpret the frequency-dependent response in terms of equivalent-circuit model of contact resistance $R_s$ in series with two parallel combination of $R_{TPD},\;C_{TPD}\;and\;R_{Alq3},\;C_{Alq3}$.

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Electrical Characteristics of Organic Light Emitting Diodes (OLED) using the cathode change (다양한 혼합 전극을 사용한 Organic Light Emitting Diodes(OLEDs)의 전기적 특성)

  • Lee, Hyun-Koo;Kim, Jun-Ho;Kim, Young-Kwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.475-476
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    • 2005
  • Efficient electron injection is essential to achieve bright and efficient organic light-emitting diodes (OLEDs). In spite of high work function of Al, it is a common cathode because of its stability. In this paper, to overcome the poor electron injection in OLEDs with Al cathode, OLEDs with various composite cathodes were fabricated and investigated using a conventional OLEDs structure of indium tin oxide ITO/NPB(40 nm)/$Alq_3$(50 nm)/Al. composite cathodes were composed of alkaline materials such as Ca and Li, Al deposition or codeposited with AI. We showed best performance at the device with composite cathode (LiF/Al).

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Images of deposited layers of organic light-emitting diodes observed by scanning-electron microscope (주사 전자 현미경으로 관찰한 유기 발광 소자의 누적층 모양)

  • Lee, Eun-Hye;Yoon, Hee-Myoung;Han, Wone-Keun;Kim, Tae-Wan;Lee, Won-Jae;Jang, Kyung-Uk;Ahn, Joon-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.298-299
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    • 2008
  • Images of deposited layers of organic light-emitting diodes were observed by scanning-electron microscope (SEM). We were able to see a clear cross-sectional view of deposited layers. The SEM is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. A thickness of deposited layer measured by thickness monitor is close to a real value measured by a-step surface profiler within 5%. We were able to see a formation of domains of size about 50-100nm from a surface morphology of Al, and pin holes of size about 50nm.

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A Study on the Dielectric Polarization of Organic Light-Emitting Diodes (유기 발광 다이오드의 유전분극에 관한 연구)

  • Oh, Y.C.;Chung, D.H.;Shin, C.G.;Kim, J.S.;Kim, K.J.;Kim, S.J.;Kim, C.H.;Kim, T.W.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.490-491
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    • 2007
  • We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum$(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric polarization of organic light emitting diodes using impedance. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of 40Hz to $10^8Hz$. We obtained dielectric constant and loss tangent (tan ${\delta}$) of the device. From these analyses, we are able to interpret a dielectric dispersion and dielectric absorption contributed by an interfacial and orientational polarization.

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Modified Poly(3,4-ethylenedioxythiophene) with Poly(ionic liquid)s as a new hole injecting materials in organic light emitting diodes (OLEDs)

  • Kim, Earl;Kim, Tae-Young;Suh, Kwang-Seok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.132-132
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    • 2010
  • In a previous report, we demonstrated that poly (3,4-ethylenedioxythiophene) derived from poly (ionic liquid) (PEDOT:PIL) constitutes a polymeric hole-injecting material capable of improving device lifetime in organic light-emitting diodes (OLEDs).was attributed to aprotection characteristic of PEDOT:PIL for the indium extraction from ITO electrodes, which frequently occurrs in the OLED device with the conventional PEDOT materials. In this study, we report the OLED device lifetime as well asvice efficiencycan be further improved with the modified PEDOT:PIL in whichorganic compounds are incorporated. The deviced performance will be presented in terms of device lifetime and efficiencies.

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