• Title/Summary/Keyword: White voltage

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Improvement in the Stabilities of White Organic Light Emitting Diodes Using a Partially Doped Emission Layer

  • Jeon, Hyeon-Sung;Oh, Hwan-Sool;Yoon, Seok-Beom
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.3
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    • pp.145-148
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    • 2010
  • White organic light emitting devices were fabricated to improve the stability through a structural change using the two peak emission method. The fabricated devices were composed of indium tin oxide (100 nm)/ $\alpha$-NPD (30 nm)/4,40-bis(2,20-diphenylvinyl)-1,10-biphenyl (DPVBi, d: variable)/DPVBi: Rubrene (40 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline(5 nm)/ $Alq_3$(5 nm)/ Al (100 nm). A DPVBi for blue emissions was used as the host material in the emitters. The doping concentration of the Rubrene was fixed at 2.0% (by weight). The white emission with Commission Internationale De L'Eclairage coordinates of (0.3342, 0.3439) occurred at 14 V with a thickness d of 1 nm. It was insensitive to the drive voltage, and the devices had a maximum luminance of $211\;cd/cm^2$. At 19 V, the current density and maximum external quantum efficiency were $173\;mAcm^2$ and 0.478%, respectively.

The Fabrication and Characteristics of White Organic Light-Emitting Diodes using Blue and Orange Emitting Materials (청색과 오렌지색 발광재료를 사용한 백색 유기발광소자 제작 및 특성 분석)

  • Kang, Myung-Koo
    • 전자공학회논문지 IE
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    • v.43 no.2
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    • pp.1-6
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    • 2006
  • The white organic light emitting diode(OLED) with two-wavelength was fabricated using the DPVBi of blue emitting material and a series of orange colar fluorescent dye(Rubrene) by vaccum evaporation processes. The basic structure of OLED was ITO/TPD$(225{\AA})$/DPVBi/Rubrene/BCP$(210{\AA})/Alq_3(225{\AA})/Al(1000{\AA})$. We analyzed the fabricated device through the changes of the DPVBi and Rubrene layer's thickness. We obtained the white OLED with the CIE coordinate of the device was (0.29, 0.33) and luminescence of $1000cd/m^2$ at applied voltage of 15V when 4he thickness of DPVBi layer was 210${\AA}$ and the thickness of Rubrene layer was 180${\AA}$.

Analysis of the Optical and Electrical Properties of a White OLEDs Using the newly Synthesized Blue Material (신규 합성 청색재료를 사용한 백색 유기발광소자의 광학적$\cdot$전기적 특성평가)

  • Yoon Seok Beom
    • Journal of the Korea Society of Computer and Information
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    • v.10 no.1 s.33
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    • pp.1-6
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    • 2005
  • White light emission is very important for applying electroluminescent device to full display, backlight and illumination light source. In this letter, Multilayer molecular organic white-light-emitting device using thin nim of blue material nitro-DPVT with fluorescent dye Rubrene for an orange emission were fabricated. The basic structure of the fabricated device is a-NPD / nitro-DPVT / nitro- DPVT:Rubrene / BCP/ Alq3. Aluminum is used as the cathode material and ITO was anode material. The white light emission spectrum covers a wide range of the visible region and the Commission Internationale do I'E clairage (C.I.E.) coordinates of the emitted light was ((0.3347, 0.3515) at 14V. The turn voltage is as low as 2.5V and quantum efficiencies are $0.35\%$.

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High Efficiency Hybrid White Organic Light-Emitting Diodes for Reduced Efficiency Roll-Off and Color Stability

  • Seo, Ji-Hoon;Park, Jung-Sun;Kim, Jun-Ho;Koo, Ja-Ryong;Seo, Bo-Min;Lee, Kum-Hee;Park, Jeong-Keun;Je, Jong-Tae;Yoon, Seung-Soo;Kim, Young-Kwan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.418-420
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    • 2009
  • The Authors have demonstrated high efficiency hybrid white organic light-emitting diodes (HWOLED) for reduced efficiency roll-off and color stability. It was shown that HWOLED fabricated in this study have the maximum luminance of 46 420 cd/$m^2$ at 8 V (turn-on voltage of 2.7 V), external quantum efficiency of 13.18%, power efficiency of 28.75 lm/W at 1 000 cd/$m^2$, and reduced efficiency roll-off of 2.7 times than control white device. The HWOLED also showed the stable color shift with $\Delta$Commission Internationale de I'Eclairage coordinates coordinates of ${\pm}$ (0.00, 0.00) from 100 to 10000 cd/$m^2$.

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Significant Improvements in White OLED Color Purity by Doping Ratio of $(POB)_{2}Ir(pic)$ ($(POB)_{2}Ir(pic)$의 doping 비율에 따른 White OLED의 색순도 향상에 관한 연구)

  • Kim, Dong-Eun;Kim, Byoung-Sang;Park, Jae-Chu;Chang, Jeong-Soo;Kwon, Young-Soo
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1373-1374
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    • 2007
  • We has been synthesized $(POB)_{2}Ir(pic)$ as a red emitting materials and evaluated in the organic light emitting diodes (OLED). The layer of $Alq_3$ doped with $(POB)_{2}Ir(pic)$ as emitters has been demonstrated. The structure of the device is ITO/ NPB (40 nm) / $Zn(HPB)_2$ (40 nm)/ $Alq_3$ : $(POB)_{2}Ir(pic)$ (30 nm) / LiF / Al. We varied the doped rate of $(POB)_{2}Ir(pic)$. The doped rate is 0.4 %, 0.6%, 0.8 and 1.2%, respectively. When the doped rate of the $Alq_3$:$ Ir(POB)_{2}(pic)$ was 0.6%, white emission is achieved. The Commission Internationale de l'Eclairage (CIE) coordinates of the white emission are (0.316, 0.331) at an applied voltage of 10.75V.

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White Oganic Light-Emitting Diodes based on Simply Modified Anthracene and Rubrene (안트라센의 단순 유도체와 루브렌을 이용한 백색 유기전기발광소자)

  • Kim, Si-Hyun;Lee, Seung-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.39 no.5
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    • pp.589-595
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    • 2022
  • The white OLED is fabricated with the anthracene-based blue emitting material, 9-(2-naphthyl)-10-(p-tolyl)anthracene (2-NTA) in various volume-ratios of orange dopant, rubrene, which results in pure white emission with C.I.E. coordinate of ~(0.32, 0.39). The devices with <1.5% rubrene show better EL properties (efficiency) than >3% devices. Furthermore the turn-on voltage of 2-NTA WOLED (3.7 V) is lower than that of 2-NTA blue OLED (5.4 V) at the same condition. Conclusively 2-NTA with rubrene less than 1.5% (v/v) could be utilized for the pure WOLED.

An Analysis of a Phase Locked AM signal Detection (위상고정회로를 사용한 AM신호 검파방식의 해석)

  • 문상재
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.13 no.5
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    • pp.24-29
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    • 1976
  • In the phase locked AM signal detection, phase locked loop is used to extract a synchronous carrier from an input AM signal. Under the assumption that input noise is white Gaussian and free-running frequency of voltage controlled oscillator is the same that of an input carrier, operational behaviours of phase locked loop is analyzed and signal to noise ratio of the detection is derived quentitatively. The results show that the phase locked AM signal detection method offers a higher degree of noise mmunity than conventional AM signal detections.

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A Study on Response Characteristics of Photoelectric Type Smoke Detector Chamber Due to Dust Color (분진색상에 따른 광전식연기감지기 챔버의 응답특성에 관한 연구)

  • Lee, Ho-Sung;Kim, Si-Kuk
    • Fire Science and Engineering
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    • v.31 no.5
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    • pp.44-52
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    • 2017
  • This paper is based on a study of the response characteristics of photoelectric type smoke detector chambers according to dust color. Due to an amendment to the Fire Safety Codes to automatic fire alarm systems and visual alarm device, the installation of indoor smoke detectors has become mandatory, but in Korea there is still insufficient research on the non-operation or false alarms that could arise in indoor environments by indoor dust and other environmental conditions etc. In light of this, for this study, research was conducted on the indoor adaptability of smoke detector under various colors of fiber dust that were judged to occur most frequently in among the common indoor dust, photoelectric smoke detector with the lattice-type smoke detection chamber that the smoke detector which is most popular in the country was used, and four colors of fiber dust (brown, white, gray and black) were used the test dusts for carrying out dust and sensitivity testing. Also, the voltage of the photocell part of the smoke chamber was measured, and the scattering phenomenon in the chamber was observed. The result of the testing showed that all four dust types were suitable for dust and sensitivity testing under conditions of pollution A. Yet, there were occasions, at pollution B or C, where the brown, white and gray dust would cause fail alarm during operation testing. And black dust was confirmed to cause non-operation during operation testing. In the case of brown and white dust, the voltage measurement result of the photocell part of the smoke chamber confirmed that the voltage increases as the pollution level increases, and in the case of gray and black dust, the voltage decreases.

Fabrication and Characteristics of Electroluminescent Lamp (전계발광램프의 제작 및 특성)

  • 박욱동;최규만;최병진;김기완
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.5
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    • pp.101-105
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    • 1994
  • The EL lamp have been fabricated by screen printing method. the thickness of BaTiO$_3$ dielectric layer and ZnS:Cu phosphor layer was 20 $\mu$m and 40 $\mu$m, respectively. The threshold voltage of green El lamp was 50 $V_{p-p}$ and the maximum brightness was 13.5 $\mu$ W/cm$^2$ at frequency of 700 Hz and the input voltage of 250 $V_{p-p}$. Also when the Rodamin G6 of 0.02 g was doped, the threshold voltage of white EL lamp was 70 $V_{p-p}$ and the maximum brightness was 34 $\mu$W/cm$^2$.

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A Study on High Viscosity Phosphor Dispensing Process for Implementation of High-Efficiency White LED (고효율 백색 발광다이오드 구현을 위한 고점도 형광체 정량 토출 공정 연구)

  • Yang, Young-Jin;Kim, Hyung-Chan;Ko, Jeong-Beom;Yang, Bong-Su;Dang, Hyun-Woo;Doh, Yang-Hoi;Cho, Kyung-Ho;Choi, Kyung-Hyun
    • Clean Technology
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    • v.20 no.2
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    • pp.97-102
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    • 2014
  • Currently various studies are underway for dispensing high-viscosity phosphor. These studies have reported limitations and challenges in the dispensing process. The discharged amount of phosphor was approximately the same each time which is important for the implementation of high-efficiency white LED technology. This paper present high-viscosity phosphor dispensing process for white LED implementation by using electrostatic printing technology. The voltage controlled DOD (Drop-On-Demand) discharge experiment was studied to determine angle of drop meniscus at nozzle and dot diameter. With increase in Discharge voltage, the discharge angle of meniscus increased while dot diameter decreased. Therefore it can be concluded that we can control the discharge rate by controling the discharge angle of meniscus.