• Title/Summary/Keyword: Blue device

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High efficiency deep blue and pure white phosphorescent organic light emitting diodes

  • Yook, Kyoung-Soo;Jeon, Soon-Ok;Joo, Chul-Woong;Kim, Myung-Seop;Choi, Hong-Seok;Lee, Seok-Jong;Han, Chang-Wook;Tak, Yoon-Heung;Lee, Nam-Yang;Lee, Jun-Yeob
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.486-488
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    • 2009
  • High efficiency deep blue and pure white phosphorescent organic light emitting diodes were developed using a new deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium (FCNIr). A high quantum efficiency of 9.1 % with a color coordinate of (0.15, 0.16) at 1,000 cd/$m^2$ was obtained in the deep blue device and a high quantum efficiency of 15.2 % with a color coordinate (0.30, 0.32) was obtained in the pure white organic light-emitting diodes. The quantum efficiency of the pure white device is the best quantum efficiency value reported in the pure white device up to now.

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Improved EL efficiency and operational lifetime of top-emitting white OLED with a co-doping technology

  • Lee, Meng-Ting;Tseng, Mei-Rurng
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08b
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    • pp.1411-1414
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    • 2007
  • We have developed a top-emitting white organic electroluminescent device (TWOLED) incorporating a low-reflectivity molybdenum (Mo) anode and doped transport layers as well as a dual-layer architecture of doped blue and yellow emitters with the same blue host. The EL efficiency and operational lifetime of TWOLED can be enhanced by a factor of 1.2 and 3.4 than that of standard TWOLED, respectively, with a co-doping technology in yellow emitter by doping another blue dopant. The enhancement in device performances can be attributed to improve the energy transfer efficiency from blue host to yellow dopant through a blue dopant as medium in yellow emitter.

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Effects of Electron Transport Layers on Electrical and Optical Characteristics of Blue Phosphorescent Organic Light Emitting Diodes (전자수송층이 청색 인광 OLED의 전기 및 광학적 특성에 미치는 영향)

  • Suh, Won-Gyu;Moon, Dae-Gyu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.4
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    • pp.323-326
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    • 2009
  • We have developed blue-emitting phosphorescent organic light emitting diodes (OLEDs) using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tris (8-quinolinolato)aluminum ($Alq_3$) electron transport layers. As blue dopant and host materials, bis[(4,6-di-fluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) and N,N'-dicarbazolyl-3,5-benzene (mCP) were used, respectively. The driving voltage, current efficiency and emission characteristics of devices were investigated. While the driving voltage was about $1{\sim}2$ V lower in the device with an $Alq_3$ layer, the current efficiency was about 66 % higher in the device with BCP electron transport layer. the blue phosphorescent OLED with BCP layer exhibited higher purity of color, resulting from a relatively weak electroluminescence intensity at 500 nm.

Energy Transfer and Emission Properties of Organic Electroluminescent Device According to Polymer/Dye Mixing Ratio (고분자/저분자 발광재료의 혼합비에 따른 유기 전계발광 소자의 에너지 전달 및 발광특성)

  • Kim, Ju-Seung;Seo, Bu-Wan;Gu, Hal-Bon;Lee, Kyung-Sup;Park, Bok-Kee
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.997-999
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    • 1999
  • We fabricated white light-emitting organic electroluminescent device which have a mixed single emitting layer containing poly(N-vinylcarbazole)[PVK], tris(8-hydroxyquinoline)aluminum[Alq3] and poly(3-hexylthiophene)[P3HT] and investigated the emission properties of it. We expect to obtain a blue light from PVK, green light from Alq3 and red light from P3HT The fabricated device emits white light over 18V with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to $Alq_3$ and P3HT resulted in decreasing the blue light intensity from PVK. With mixing of N, N'-diphenyl-N, N'-(3-methylphenyl)-[1,1'-biphenyl]-4, 4'-diamine[TPD], hole transport material, to the emitting layer, the luminance intensity of device was increased 50 times than that of the device which not contain TPD. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.

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Barrier Layers and Pulsed Laser Annealing Effects on TFEL Device with Cu and Ag co-doped SrS blue Phosphor Layer

  • Nam, Tae-Sung;Liew, Shan-Chun;Koutsogeorgis, Demosthenes C;Cranton, Wayne M
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.910-913
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    • 2003
  • In order to enhance performance, stability, and brightness of inorganic blue-light emitting EL device, barrier layer structure and pulsed laser annealing(PLA) treatment were introduced. The barrier layer structure was utilized for improving brightness of the device and instead of thermal annealing, pulsed laser annealing process was used. From this study, optimum barrier layer thickness and number of pulsed laser irradiation are established.

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Analysis of Characteristics of the Blue OLEDs with Changing HBL Materials (정공 저지층의 재료변화에 따른 청색유기발광소자의 특성분석)

  • Kim, Jung-Yeoun;Kang, Myung-Koo;Oh, Hwan-Sool
    • 전자공학회논문지 IE
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    • v.43 no.4
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    • pp.1-7
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    • 2006
  • In this paper, two types of blue organic light-emitting device were designed. We have analyzed the characteristics of Type I device without a hole blocking layer, and analyzed the characteristics of Type II device using a hole blocking layer of BCP or BAlq materials with 30 ${\AA}$ thickness. We obtained the ITO having the work function value of 5.02 eV using $N_2$ plasma treatment method with the plasma power 200 W. Type I device structure was ITO/2-TNATA/$\alpha$-NPD/DPVBi/$Alq_3$/LiF/Al:Li, and type II device structure was ITO/2-TNATA/$\alpha$-NPD/DPVBi/HBL/$Alq_3$/LiF/Al:Li. We have analyzed the characteristics of Type I and Type II device. The characteristics of the device were most efficiency on occasion of using a hole blocking layer of BAlq material with 30 ${\AA}$ thickness. Current density was 226.75 $mA/cm^2$, luminance was 10310 $cd/m^2$, Current efficiency was 4.55 cd/A, power efficiency was 1.43 lm/W at an applied voltage of 10V. The maximum EL wavelength of the fabricated blue organic light-emitting device was 456nm. The full-width at half-maximum (FWHM) for the EL spectra was 57nm. CIE color coordinates were x=0.1438 and y=0.1580, which was similar to NTSC deep-blue color with CIE color coordinates of x=0.14 and y=0.08.

Blue Light Emitting Electroluminescence Diode (Coronene을 이용한 청색 유기전계 발광 소자의 개발)

  • Lim, Sung-Taek;Shin, Dong-Myung;Roh, Suk-Won
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1377-1378
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    • 1998
  • Blue light emitting electroluminescence(EL) diodes were fabricated utilizing Coronene and some organic materials. Coronene showed photoluminescence(PL) peak at 450nm in solution with high quantum efficiency. Multi layer system was applied to fabricate EL diode utilizing Coronene. The device showed didode-like applied voltage-current relationship. And blue light emitting was observed. The decay time of device was in a scale of some seconds. The trun-on voltage of device was about 9 V.

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Development & Reliability Verification of Ultra-high Color Rendering White Artificial Sunlight LED Device using Deep Blue LED Light Source and Phosphor (Deep Blue LED 광원과 형광체를 이용한 초고연색 백색 인공태양광 LED 소자의 개발)

  • Jong-Uk An;Tae-Kyu Kwon
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.46 no.3
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    • pp.59-68
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    • 2023
  • Currently, yellow phosphor of Y3Al5O12:Ce3+ (YAG:Ce) fluorescent material is applied to a 450~480nm blue LED light source to implement a white LED device and it has a simple structure, can obtain sufficient luminance, and is economical. However, in this method, in terms of spectrum analysis, it is difficult to mass-produce white LEDs having the same color coordinates due to color separation cause by the wide wavelength gap between blue and yellow band. There is a disadvantage that it is difficult to control optical properties such as color stability and color rendering. In addition, this method does not emit purple light in the range of 380 to 420nm, so it is white without purple color that can not implement the spectrum of the entire visible light spectrum as like sunlight. Because of this, it is difficult to implement a color rendering index(CRI) of 90 or higher, and natural light characteristics such as sunlight can not be expected. For this, need for a method of implementing sunlight with one LED by using a method of combining phosphors with one light source, rather than a method of combining red, blue, and yellow LEDs. Using this method, the characteristics of an artificial sunlight LED device with a spectrum similar to that of sunlight were demonstrated by implementing LED devices of various color temperatures with high color rendering by injecting phosphors into a 405nm deep blue LED light source. In order to find the spectrum closest to sunlight, different combinations of phosphors were repeatedly fabricated and tested. In addition, reliability and mass productivity were verified through temperature and humidity tests and ink penetration tests.

Development of Highly Efficient and Stable Blue Organic Electroluminescent Devices

  • Lee, Meng Ting;Chen, Hsia Hung;Tsai, Chih Hung;Liao, Chi Hung;Chen, Chin H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.265-268
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    • 2004
  • We have developed a highly efficient and stable blue organic electroluminescent device (OLED) based on the blue fluorescent p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph) dopant in a morphologically stable high-bandgap host material, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN), which achieved an EL efficiency of 9.7 cd/A and 5.5 lm/W at 20 mA/$cm^2$ and 5.7 V with a Commission Internationale d'Eclairage coordinates of(x = 0.16, y = 0.32). This sky blue device which could also alleviate the problematic current induced quenching at high current achieved a half-decay lifetime ($t_{1\;2}$) of 46,000 h at an initial brightness of 100 cd/$m^2$.

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Electrical and Optical Properties of Organic Light Emitting Devices Using Blue Fluorescent and Orange Phosphorescent Materials (청색형광재료와 황색인광 재료를 이용한 OLEDs의 전기 및 광학적 특성)

  • Seo, Yu-Seok;Moon, Dae-Gyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.155-155
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    • 2010
  • We have investigated organic light-emitting devices by doping phosphorescent orange and fluorescent blue emitters into the separate layers of single host. The electroluminescence spectra and current efficiency were strongly dependent on the location of each doped layers. The luminance-voltage (L-V) characteristics of the device2 (ITO/Hole Transport Layer/Orange Phosphorescent emissive layer/Blue Fluorescent emissive layer/Electron Transport Layer/liF/Al) showed the maximum current efficiency of 19.5 cd/A.

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