Bright white light electroluminescent devices based on a dye-dispersed polyfluorene derivative

Kim, Joo Hyun; Herguth, Petra; Kang, Mun‐Sik; Jen, Alex K.‐Y.; Tseng, Ya-Hsien; Shu, Ching‐Fong

doi:10.1063/1.1778472

Cited by 85 publications

(47 citation statements)

References 14 publications

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“…4 Kim et al showed that bright white PLEDs could be produced using a blend of two fluorescent dyes in a blue emission polyfluorene derivative as a light-emitting layer. 8 Mikami et al reported that white PLEDs with high brightness, efficiency, and color purity could be fabricated using a single light emitting layer of fluorescent dye doped polymers. 10 Gong et al showed that white PLEDs with excellent electroluminescence (EL) properties could be fabricated using a phosphorescent-Ir complex doped polymer as a lightemitting layer.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

Lee

Hsu

2007

J of Applied Polymer Sci

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A series of triarylaminooxadiazole-containing tetraphenylsilane light emitting polymer (PTOA) and poly(2-methoxy, 5-(2 0 -ethyl-hexyloxy)-p-phenylene-vinylene) (MEH-PPV) based white light emitting polymer devices (PLEDs) were fabricated to study blue and orange-red emitter composition and light emitting layer processing effects on white emission electroluminescence properties. Color purity, current turn-on voltage, brightness, and current efficiency were strongly determined by MEH-PPV content and the thin film processing condition. The intensity of PTOA blue emission was equal to that of MEH-PPV orange-red emission when the device was fabricated by a polymer composite film containing 10 wt % of MEH-PPV. Color purity [Commission Internationale de L'Eclairage (CIE x,y ) coordinates (0.26,0.33)] was nearly white emission under applied 8 V. The brightness and current efficiency of PTOA-MEH-PPV composite film based devices increased as MEH-PPV content increased. Furthermore, white emission blue shifted with increasing spin-rate of thin film coating and applied voltage. Low turn-on voltage, high current density, and high brightness were obtained for the device fabricating with light emitting layer coating with high spin-rate. Moreover, low current efficiency was obtained for the PLED with a thinner light-emitting layer. A white emission CIE (0.28,0.34) was obtained for PTOA-MEH-PPV based white PLED. White PLED brightness and efficiency can be as high as 700 cd/m 2 and 0.78 cd/A, respectively.

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Section: Introductionmentioning

confidence: 99%

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

Lee

Hsu

2007

J of Applied Polymer Sci

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“…Several strategies toward realizing PWLEDS have been reported, such as the multilayer-device system [3][4][5] and the single-layer polymer-blend system. [6][7][8][9][10][11][12] Nevertheless, both of them have some disadvantages, for instance, the interfacial mixing of different layers for the former and the intrinsic phase separation for the latter, which limit their applications. These problems are avoidable in a single-polymer system.…”

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confidence: 99%

White Electroluminescence from a Phosphonate‐Functionalized Single‐Polymer System with Electron‐Trapping Effect

et al. 2009

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Organic and polymeric white-light-emitting diodes (OWLEDs and PWLEDs) have attracted great attention due to their potential applications in full-color displays, back lighting, and solid-state lighting sources. [1,2] Compared with OWLEDS based on small-molecule emitters, PWLEDS are of particular interest because they can be fabricated by a simple and low-cost solution-manufacturing process. Several strategies toward realizing PWLEDS have been reported, such as the multilayer-device system [3][4][5] and the single-layer polymer-blend system. [6][7][8][9][10][11][12] Nevertheless, both of them have some disadvantages, for instance, the interfacial mixing of different layers for the former and the intrinsic phase separation for the latter, which limit their applications. These problems are avoidable in a single-polymer system. Although this approach has been demonstrated in several white-light-emitting polymers with blue-light emission from the polymer itself and orange-light emission from aggregation/ excimer, [13][14][15][16] this kind of white electroluminescence (EL) suffers from low efficiency and spectral dependence on bias.In our previous work, we proposed a series of strategies to obtain two-and three-color white light from a single-polymer system with different emission components, based on the control of partial energy transfer from host to dopant and charge trapping on the dopant. [17][18][19][20][21][22][23][24][25] For example, one approach for two-color white emission is to incorporate an orange component as dopant to the main chain or the side chain of a blue-light-emitting polymer host, [17][18][19][20] and to use orange-light emissive species as the central core and a blue-light-emitting polymer as the outer arms.[21] Another method for three-color emission is to covalently attach both a green chromophore and a red chromophore to a blue-emissive polymer host with different attachments, [22] and to use blue, green, and red dopant units as individual emissive species and polyfluorene (PF) as individual polymer host. [25] Recently, these approaches have been demonstrated in several single-polymer systems. For instance, Cao et al., [26][27][28] Shu et al., [29][30][31] Shim et al., [32][33][34] Hsu et al., [35,36] and Chen et al. [37] have also succeeded in realizing white EL from a single polymer based on the partial energy transfer and charge-trapping mechanism. However, all of the single white-light-emitting polymers reported so far, regardless of being two-or three-color and singlet or mixed singlet and triplet emission, are achieved based on the partial energy transfer and charge trapping on dopant in the EL process. Herein, we propose a novel strategy to realize two-color white EL from a single polymer based on the mechanism of electron trapping on host rather than charge trapping on dopant (see Figure 1). The electron trapping on host or host pendant is expected to suppress the charge transfer from host to dopant, which results in balanced individual emissions from the blue host and long-waveleng...

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“…[1][2][3][4][5][6][7][8][9][10][11][12] One of main approaches to producing WPLEDs is to use a polymer blend system, such as three-polymer blends containing red, green and blue polymers, 13 and blends consisting of two or three kinds of fluorescent dyes in an efficient blue-emitting polymer matrix. 14,15 However, it is difficult to obtain highly efficient and color stable WPLEDs using polymer blend systems due to undesirable Forster-type energy transfer between chromophores. Another approach is to use single layer devices made from homopolymers 16,17 or copolymers.…”

Section: Introductionmentioning

confidence: 99%

White Electroluminescence from Bicarbazyl-containing Conjugated Polymers as Single-Emitting Component

2008

Bulletin of the Korean Chemical Society

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Two bicarbazyl-containing fluorene copolymers, PFEBCz (95/5) and PFEBCz (75/25), were synthesized for white light electroluminescence from a single emitting polymer. All synthesized polymers were soluble in common organic solvents such as chloroform and toluene. The weight-average molecular weights (M w ) of the PFEBCz (95/5) and PFEBCz (75/25) copolymers were found to be 11,000 and 5,700 with polydispersity indices 1.4 and 1.8. The EL spectrum of the PFEBCz (75/25) device showed bright white-light emission with CIE coordinates of (0.32, 0.34) at 1000 cd/m 2 , which is very close to that for pure white (0.33, 0.33). This white emission may have been due to strong excimer formation between the bicarbazyl and fluorene polymer backbone. The device exhibited a maximum brightness of 3400 cd/m 2 with a maximum efficiency of 0.2 cd/A.

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Bright white light electroluminescent devices based on a dye-dispersed polyfluorene derivative

Cited by 85 publications

References 14 publications

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

White Electroluminescence from a Phosphonate‐Functionalized Single‐Polymer System with Electron‐Trapping Effect

White Electroluminescence from Bicarbazyl-containing Conjugated Polymers as Single-Emitting Component

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