Bright white organic light-emitting diode

Ko, Chung‐Wen; Tao, Yu‐Tai

doi:10.1063/1.1425454

Cited by 181 publications

(102 citation statements)

References 18 publications

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“…OLED는 자체 발광 소자로서 천연색 디스 플레이, 액정디스플레이(Liquid Crystal Display: LCD)의 배면광, 조명 등에 사용 가능한 높은 잠재 력을 가지고 있어 각광을 받으며 많은 연구가 진행 되었고 2) , 기판으로 유리 및 플라스틱 등의 다양한 기판을 적용할 수 있어 어떠한 형태로도 제작이 가 능하여 다양한 용도와 다양한 형태의 조명으로 사 용이 가능하다는 장점이 있다. 그러나 상용화를 위 해서는 발광효율, 소자의 수명 및 양산기술 등의 문 제점들을 개선해야 하는 상황이다 [3][4][5][6] . OLED 소자 의 효율을 개선하는 방법 중 한 가지는 인광 형광 체를 사용하는 것인데, 인광 OLED는 삼중항과 일 중항을 모두 발광에 사용하여 높은 효율을 얻을 수 있다 7,8) .…”

Section: 서 론unclassified

Emission Characteristics of White Organic Light-Emitting Diodes Using Micro Lens Array Film

Chun¹,

Na²,

Yang³

et al. 2013

Journal of the Korean institute of surface engineering

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We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with co-doping and blue/co-doping emitting layer (EML) structures were fabricated using a host-dopant system. The total thickness of light-emitting layer was 25 nm and the dopant of blue and red was FIrpic and Bt 2 Ir(acac) in UGH3, respectively. In case of co-doping structure, applying micro lens array film showed efficiency improvement from the current efficiency 78.5 cd/A and power efficiency 40.4 lm/W to the current efficiency 131.1 cd/A and power efficiency 65 lm/W and blue / co-doping structure showed efficiency improvement from the current efficiency 43.8 cd/A and power efficiency 22 lm/ W to the current efficiency 69 cd/A and power efficiency 32 lm/W.

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Section: 서 론unclassified

Emission Characteristics of White Organic Light-Emitting Diodes Using Micro Lens Array Film

Chun¹,

Na²,

Yang³

et al. 2013

Journal of the Korean institute of surface engineering

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] White-light emission in PLEDs, which is usually difficult to achieve from a single polymer, can be sought in polymer-blend systems, such as three-polymer blends containing red-, green-, and blue-light-emitting polymers; [20] two-polymer blends containing blue-and orange-light-emitting polymers; blends consisting of two polymers and an organometallic complex as the phosphorescent emitter (as reported by Müllen and co-workers [21,22] and Heeger and co-workers [23] ); and blends consisting of two or three kinds of fluorescent dyes in an efficient blue-light-emitting polymer or polymer matrix. [1,24] However, WPLEDs made by polymer-blend systems usually suffer from low efficiency and color instability.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Pure‐White‐Light‐Emitting Diodes from a Single Polymer: Polyfluorene with Naphthalimide Moieties

Mei

Zhou

et al. 2005

Adv Funct Materials

207

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Light‐emitting diodes exhibiting efficient pure‐white‐light electroluminescence have been successfully developed by using a single polymer: polyfluorene derivatives with 1,8‐naphthalimide chromophores chemically doped onto the polyfluorene backbones. By adjusting the emission wavelength of the 1,8‐naphthalimide components and optimizing the relative content of 1,8‐naphthalimide derivatives in the resulting polymers, white‐light electroluminescence from a single polymer, as opposed to a polymer blend, has been obtained in a device with a configuration of indium tin oxide/poly(3,4‐ethylenedioxythiophene)(50 nm)/polymer(80 nm)/Ca(10 nm)/Al(100 nm). The device exhibits Commission Internationale de l'Eclairage coordinates of (0.32,0.36), a maximum brightness of 11 900 cd m–2, a current efficiency of 3.8 cd A–1, a power efficiency of 2.0 lm W–1, an external quantum efficiency of 1.50 %, and quite stable color coordinates at different driving voltages, even at high luminances of over 5000 cd m–2.

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“…[1][2][3] Electrophosphorescent WOLEDs are widely considered to be the most attractive because of their high quantum and power efficiencies. In comparison with their fluorescent counterparts which can only harvest singlet excitons, phosphorescent OLEDs are able to harness both singlet and triplet excitons generated by electrical injection.…”

mentioning

confidence: 99%

Efficient White Organic Light‐Emitting Devices Based on Phosphorescent Platinum(II)/Fluorescent Dual‐Emitting Layers

et al. 2007

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White organic light-emitting devices (WOLEDs) are of great interest because they can be used in full-color flat-panel displays with color filters, backlight panels, and as alternative lighting sources. [1][2][3] Electrophosphorescent WOLEDs are widely considered to be the most attractive because of their high quantum and power efficiencies. In comparison with their fluorescent counterparts which can only harvest singlet excitons, phosphorescent OLEDs are able to harness both singlet and triplet excitons generated by electrical injection. This leads to a fourfold increase in efficiency compared to that achievable in singlet-harvesting fluorescent OLEDs.[4] White phosphorescence can be obtained from iridium(III) complexes using multiple emitting layers (EMLs), [5,6] multiply doped emissive-layer architectures, [7] or semiconducting polymer blends. [8,9] So far, the highest external quantum efficiency (g ext ) and power efficiency (g p ) achieved have been 12 % [7] and 57 lm W -1 , [10] respectively. Although the performance of phosphorescent WOLEDs have been impressive, blue electrophosphorescent devices have been shown to have short operational lifetimes that limit the color stability of all-phosphordoped WOLEDs.[11] On the other hand, the emission of the reported iridium(III) complexes usually spans about one third of the visible spectrum, [12] and more than two phosphorescent dopants are usually required to achieve balanced white-light emission. Such multiemissive-layer WOLEDs are potentially costly and complicated to fabricate. Consequently, there is a going interest in the development of WOLEDs that have high efficiencies but relatively uncomplicated architectures.To fabricate high-efficiency WOLEDs that have a relatively uncomplicated architecture, it is necessary to develop new phosphorescent materials with a broad emission spectrum and sufficiently high luminous efficiency. Herein, we describe the construction of high-efficiency WOLEDs with a phosphorescent/fluorescent dual-emitting architecture. We used fluorescent material 9,10-bis-(b-naphthyl)-anthrene (DNA) as a blue-light source to overcome the color-stability limitations found for all-phosphor-doped WOLEDs, and phosphorescent platinum(II) complexes [(RC^N^N)PtCl] (RC^N^N)PtCl) = 3-(6′-(2″-naphthyl)-2′-pyridyl)isoquinolinyl and derivatives) as an orange or green-yellow guest, doped into a 4,4′-N,N′-dicarbazole-biphenyl (CBP) host, to achieve balanced white light. The green-yellow or orange phosphorescent platinum(II) complexes described in this work contain extended p-conjugated cyclometalated ligands and exhibit broad emission spectra coving two thirds of the visible spectrum.[13] This is a significant advance towards the ultimate realization of whitelight emission using the smallest number of dopants. Although a phosphorescent/fluorescent dual-emitting architecture has recently been reported by Forrest's group, [14] there is a key difference between this study and Forrest's work. Forrest's WOLEDs are four-component devices, employing two fluorescent ...

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Bright white organic light-emitting diode

Cited by 181 publications

References 18 publications

Emission Characteristics of White Organic Light-Emitting Diodes Using Micro Lens Array Film

Emission Characteristics of White Organic Light-Emitting Diodes Using Micro Lens Array Film

Highly Efficient Pure‐White‐Light‐Emitting Diodes from a Single Polymer: Polyfluorene with Naphthalimide Moieties

Efficient White Organic Light‐Emitting Devices Based on Phosphorescent Platinum(II)/Fluorescent Dual‐Emitting Layers

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