• Title/Summary/Keyword: Organic light-emitting diode

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White Light Emission with Quantum Dots: A Review

  • Kim, Nam Hun;Jeong, Jaehak;Chae, Heeyeop
    • Applied Science and Convergence Technology
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    • v.25 no.1
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    • pp.1-6
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    • 2016
  • Quantum dots (QDs) are considered as excellent color conversion and self-emitting materials for display and lighting applications. In this article, various technologies which can be used to realize white light emission with QDs are discussed. QDs have good color purity with a narrow emission spectrum and tunable optical properties with size control capabilities. For white light emission with a color-conversion approach, QDs are combined with blue-emitting inorganic and organic light-emitting diodes (LED) to generate white emission with high energy conversion efficiency and a high color rendering index for various display and lighting applications. Various device structures for self-emitting white QD light-emitting diodes (QD-LED) are also reviewed. Various stacking and patterning technologies are discussed in relation to QD-LED devices.

Conduction mechanism in organic light-emitting diode in ITO/PEDOT/PSS/TPD/Alq$_3$/LiAl structure (ITO/PEDOT/PSS/TPD/Alq$_3$/LiAl 구조의 유기 발광 소자에서 전도 메카니즘)

  • 정동회;김상걸;정택균;오현석;이원재
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.198-201
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    • 2002
  • We have studied the temperature dependence of current-voltage and luminance-voltage characteristics of Organic Light Emitting Diodes(OLEDs). The OLEDS are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum(III) (Alq$_3$) as an electron transport, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a buffer layer. The current-voltage and luminance-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs has been interpreted in terms of space-charge-limited current(SCLC) and tunneling mechanism.

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Improved Efficiency and Lifetime for Organic Light-emitting Devices based on Mixed-hole Transporting Layer (혼합된 정공 수송 층을 이용한 유기발광소자의 효율 및 수명 개선)

  • Seo, Jl-Hyun;Park, Jung-Hyun;Park, Il-Hong;Kim, Jun-Ho;Kim, Young-Kwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.3
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    • pp.257-262
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    • 2007
  • Organic light-emitting diodes (OLEDs) with the high efficieney and long lifetime are of growing interest in next-generation displays. Among the factors influencing OLEDs properties, one of unstable factor is $Alq_3$ cationic species caused by the excess holes resided in $Alq_3$ layer. Therefore, we suppressed the accumulation of excess holes by using the mixed-hole transporting layer (MHTL) of NPB and CBP in multilayer green OLEDs. The devices with MHTL showed improved characteristics in the luminous efficiency and lifetime. More characteristics and the carrier transport mechanism will be discussed.

Pyromellitic dianhydride as a cathode interfacial layer in the organic light emitting diodes: thickness optimization and its electroluminescent characteristics

  • Nam, Eun-Kyoung;Moon, Mi-Ran;Son, Dong-Jin;Park, Keun-Hee;Jung, Dong-Geun;Kim, Hyoung-Sub
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.837-838
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    • 2009
  • In this work, pyromellitic dianhydride (PMDA) was used as a cathode interfacial layer in the organic light emitting diodes (OLEDs) and its thickness was optimized. Various electrical and optical characterizations of the OLEDs having various thicknesses of the PMDA cathode interfacial layer revealed that the best OLED performance could be achieved by using 0.5 nm-thick PMDA layer compared to the control device without any interfacial layer.

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A Simple Structural Red Phosphorescent Organic Light-Emitting diodes with high-efficiency and low-voltage

  • Seo, Ji-Hyun;Jin, You-Young;Kim, Hoe-Min;Choi, Eun-Young;Kim, Jun-Ho;Lee, Kum-Hee;Yoon, Seung-Soo;Kim, Young-Kwan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.46-48
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    • 2009
  • We demonstrated that the simple layered red phosphorescent organic light-emitting diodes are possible to have high efficiency and low driving voltage without hole injection and transport layers. The simplified OLED shows the max. current efficiency, power efficiency and quantum efficiency of 26.3 cd/A, 20.7 lm/W and 16.7 %, respectively.

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Study on the ITO Pre-treatment for the Highly Efficient Solution Processed Organic Light-emitting Diodes (고효율의 용액공정용 유기 발광 다이오드 제작을 위한 ITO 전처리 연구)

  • Choi, Eun-Young;Seo, Ji-Hyun;Choi, Hak-Bum;Je, Jong-Tae;Kim, Young-Kwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.1
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    • pp.18-23
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    • 2010
  • We demonstrated that the solution processed organic light-emitting diodes (OLEDs) have the high efficiency with pre-treated indium-tin-oxide (ITO). ITO surface was pre-treated with four methods and compared each other. The pre-treatment of ITO surface improves the chemical and physical characteristics of ITO such as the surface roughness, adhesion property, and the hole injection ability. These properties were analyzed by the contact angle, atomic force microscope (AFM) image, and the current flow character in device. As a results, the device with ITO pre-treated by $O_2$ plasma shows the current efficiency of 5.93 cd/A, which is 1.5 times the device without pre-treatment.

Study of OLED luminescence efficiency by electron Injection layer change (유기발광 소자의 전자 주입층 두께 변화에 따른 발광효율 연구)

  • Lee, Jung-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.555-558
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    • 2004
  • The efficiency of electron injection from the cathode is strongly dependent on the thickness of the LiF buffer-layer. We used LiF to electron Injection layer. We compared characteristics of organic light emitting device changing LiF thin film thickness from 1.0 m to 10.0 nm. Experiment result, we found that LiF thickness has the optimized electrical characteristics in 3.0 m. In this paper, we did research about electrical characteristics of organic light emitting device by LiF thickness change using method numerical analysis method. We proved adequate experimental results that compare results of numerical analysis, and come out through an experiment results is validity.

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Ultra-High Resolution and Large Size Organic Light Emitting Diode Panels with Highly Reliable Gate Driver Circuits

  • Hong Jae Shin
    • International journal of advanced smart convergence
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    • v.12 no.4
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    • pp.1-7
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    • 2023
  • Large-size, organic light-emitting device (OLED) panels based on highly reliable gate driver circuits integrated using InGaZnO thin film transistors (TFTs) were developed to achieve ultra-high resolution TVs. These large-size OLED panels were driven by using a novel gate driver circuit not only for displaying images but also for sensing TFT characteristics for external compensation. Regardless of the negative threshold voltage of the TFTs, the proposed gate driver circuit in OLED panels functioned precisely, resulting from a decrease in the leakage current. The falling time of the circuit is approximately 0.9 ㎲, which is fast enough to drive 8K resolution OLED displays at 120 Hz. 120 Hz is most commonly used as the operating voltage because images consisting of 120 frames per second can be quickly shown on the display panel without any image sticking. The reliability tests showed that the lifetime of the proposed integrated gate driver is at least 100,000 h.

Numerical Simulations of Electric-Optical Characteristics for Organic Light Emitting Diode with Gradient-Doped Emitting Layer (경사 도핑된 발광층을 갖는 유기발광다이오드의 전기광학적 특성 해석)

  • Lee, Young-Gu;Oh, Tae-Sik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.8
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    • pp.638-644
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    • 2010
  • We have carry out numerical simulation of the electric-optical characteristics of organic light emitting diodes with gradient-doped emitting layer which were reported to be effective in improving luminous efficiency and lifetime. In this paper, the basic structure is comprised of ITO/NPB/$Alq_3$:C545T[%]/$Alq_3$/LiF/Al, six devices by separating the emitting layer of $Alq_3$:C545T[%] were studied. As the result, the uniformly-doped devices exhibited superior luminous efficiency-current density characteristics over conventional undoped device. In the case of gradient-doped devices, electric-optical characteristics were improved similar to uniformed-doped devices, unusually the distribution of traped-charge density in the OLED devices was shown as the staircase.

Efficient red organic light-emitting devices based on electrophosphorescence (전기인광을 이용한 고효율 적색 유기 전기발광소자)

  • Song, Won-Jun;Kang, Gi-Wook;Park, Su-Yeon;Seoul, Chang;Lee, Chang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04a
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    • pp.121-124
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    • 2000
  • Achieving red light-emitting diodes with high quantum and luminous efficiency is required to fabricate the full-color organic electroluminescence display. In this work, we report that devices with 2.3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine palladium (II) (PdOEP), doped into tris(8-Hydroxyquinolinato)-aluminum (III) (Alq3) show a narrow deep red emission (670nm). In addition, PdOEP has been used as host material in which red dyes such as 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) doped in order to fabricate efficient red-emitting diodes.

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