Optimized efficiency and angular emission characteristics of white top-emitting organic electroluminescent diodes

Thomschke, Michael; Nitsche, Robert; Furno, Mauro; Leo, Karl

doi:10.1063/1.3088854

Cited by 132 publications

(97 citation statements)

References 12 publications

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“…In recent years there have been many reports of glass-based top-emissive OLEDs with good performance where Ag, 7,8 Al/Ag, 9,10 LiF/Al 12 and LiF/Al/Ag [12][13][14][15][16] have been applied as the transparent cathode, often in combination with a capping layer such as N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB), [10][11][12][13][14][15][16][17] N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD), 9 tris(8-hydroxyquinolinato)aluminium (AlQ3) 3 , 17,18 tin-doped indium oxide (ITO), SiO 2 , 15 or ZnSe. 16,19 With this second metal electrode, a microcavity resonator is obtained that amplifies a specific wavelength range and particular emission angles 15,20,21 (acting like a Fabry-Pérot filter).…”

Section: Top-emissive Oleds On Metal Foilmentioning

confidence: 99%

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

et al. 2011

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Abstract. We have investigated how to optimize the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes (OLEDs) based on metal foil substrates with the aim of creating efficient flexible devices for lighting and signage applications. By systematically varying the device architecture we were able to tune the optical microcavity which exists within the device structure and observe the change in performance. We paid particular attention to the effects of the metal foil roughness. We have seen that by changing the layer thickness of the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) [PEDOT:PSS] in the device, and the substrate reflectivity and roughness we can obtain efficacies not too far from those achieved for standard bottom-emissive devices on glass substrates made with the same emitter. The angle dependence of luminance can be tuned from pointing in the forward direction via Lambertian to having a maximum at around 65• , and we have used optical modeling to help us find the optimum device structure. We conclude that (rough) metal foils are a realistic possibility for making flexible OLEDs and have demonstrated large area (up to 12 cm × 12 cm), thin film encapsulated, flexible devices. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Top-emissive Oleds On Metal Foilmentioning

confidence: 99%

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

et al. 2011

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“…3(a) and 3(b) show the measured emission spectra of the planar reference device for observation angles θ in the range of sin θ between 0 and 1. The radiative cavity mode shows a parabolic dispersion shifting to the blue for higher emission angles [32]. The measured angular resolved emission spectra for the corrugated devices (B and C) are shown in Figs.…”

Section: Mode Analysis Of Top-emitting Oleds On Periodically Corrugatmentioning

confidence: 99%

Coherent mode coupling in highly efficient top-emitting OLEDs on periodically corrugated substrates

Schwab¹,

Fuchs²,

Scholz³

et al. 2014

Opt. Express

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Abstract:Bragg scattering at one-dimensional corrugated substrates allows to improve the light outcoupling from top-emitting organic light-emitting diodes (OLEDs). The OLEDs rely on a highly efficient phosphorescent pin stack and contain metal electrodes that introduce pronounced microcavity effects. A corrugated photoresist layer underneath the bottom electrode introduces light scattering. Compared to optically optimized reference OLEDs without the corrugated substrate, the corrugation increases light outcoupling efficiency but does not adversely affect the electrical properties of the devices. The external quantum efficiency (EQE) is increased from 15 % for an optimized planar layer structure to 17.5 % for a corrugated OLED with a grating period of 1.0 µm and a modulation depth of about 70 nm. Detailed analysis and optical modeling of the angular resolved emission spectra of the OLEDs provide evidence for Bragg scattering of waveguided and surface plasmon modes that are normally confined within the OLED stack into the air-cone. We observe constructive and destructive interference between these scattered modes and the radiative cavity mode. This interference is quantitatively described by a complex summation of Lorentz-like resonances.

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“…12 That will help to extract trapped light out of the device as well as to minimize the shift of color coordinates over viewing angle due to microcavity effect in such organic resonator devices. [13][14][15][16] Here we report improved large-area OLED devices. An advanced steel substrate for OLED integration is presented.…”

Section: Introductionmentioning

confidence: 99%

Large white organic light-emitting diode lighting panel on metal foils

Guaino

2011

J. Photon. Energy

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Abstract. Large-area top-emitting PIN structure (highly p-and n-type doped transport layers for electrons and holes and an undoped emitter layer)-organic light-emitting diode (OLED) on advanced metal foils were fabricated for lighting applications. ArcelorMittal has developed a new surface treatment on metal foils, suitable for roll-to-roll production and dedicated to large-area device integration. Both monochromatic and white devices are realized on advanced metal foils. Power efficiencies at 1000 cd/m 2 of >70 lm/W (green), moreover, power efficiency of white devices of >22 lm/W are achieved. Furthermore, first large-area 60 × 60 cm white OLED sources on metal foils are presented. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Optimized efficiency and angular emission characteristics of white top-emitting organic electroluminescent diodes

Cited by 132 publications

References 12 publications

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

Optimization of the efficacy and angle dependence of emission of top-emissive organic light-emitting diodes on metal foils

Coherent mode coupling in highly efficient top-emitting OLEDs on periodically corrugated substrates

Large white organic light-emitting diode lighting panel on metal foils

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