Light extraction from OLEDs using volumetric light scattering

Shiang, Joseph J.; Faircloth, Tami J.; Duggal, Anil R.

doi:10.1117/12.505704

Cited by 6 publications

(4 citation statements)

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“…Herein, a high refractive index contrast between the matrix polymer and scattering particles is necessary to achieve a strong volumetric scattering effect. , Typical materials for the polymeric matrix are cross-linkable acrylates, which, initially found as a monomer in solution phase, can be polymerized and cross-linked by heat and/or UV radiation. Nanoparticles with a high refractive index contrast, such as high-index TiO 2, Al 2 O 3 , or ZrO 2 − or low-index nanoscaled air voids can be embedded to introduce scattering, if their diameter d is comparable to the OLED emission wavelength λ. On the other hand, small nanoparticles with d ≪ λ have a very limited scattering effect, but can be used to increase the effective refractive index of the matrix material .…”

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confidence: 99%

Large-Area Screen-Printed Internal Extraction Layers for Organic Light-Emitting Diodes

et al. 2017

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To unleash the full potential of white organic light-emitting diodes (OLEDs) as large-area light sources, guided optical modes have to be efficiently outcoupled, which calls for internal extraction layers (IELs) that can be easily integrated into a scalable manufacturing process. To realize such IELs, we developed a high refractive index scattering polymer:TiO2-nanoparticle mixture that can be deposited onto a large area by using the cost-effective screen-printing method. We exploited this approach to produce a 10 μm thick IEL covering the exact area of active pixels distributed over a 15 × 15 cm2 glass substrate. By optimizing the initial mixture composition, we achieved screen-printing-compatible rheological properties as well as tailored light scattering and transmission over the visible spectrum. The spatial homogeneity of those optical properties was obtained by additional substrate treatments to improve the wetting behavior and to allow reflow after printing. The devices were finalized by depositing a high-efficiency white OLED stack atop the IEL. We demonstrated a luminous efficacy increase up to 56% due to the scattering layer. The IEL also ensured a Lambertian emission profile without any angular color shift.

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confidence: 99%

Large-Area Screen-Printed Internal Extraction Layers for Organic Light-Emitting Diodes

et al. 2017

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“…The OLED, as a new generation of light-emitting device, has the advantages of energy-saving, flexible, non-glare, wide-color-gamut, electroluminescence, high -efficiency, and have achieved great development [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Research on Organic Light-emitting Diode

Liu¹,

Xie²,

Ruisheng³

2019

Proceedings of the 2019 2nd International Conference on Mathematics, Modeling and Simulation Technologies and Applications (MMS

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As a new generation of light source, the organic light-emitting diode (OLED) has many advantages, and Apple has adopted OLEDs display on the latest version of mobile phones. However the low light output rate is an important factor restricting its performance. In this paper, FDTD solutions software is used to design the new OLEDs device structure and carry out optical simulation. The light extraction efficiency (LEE) enhancement is investigated. The results provide theoretical guidance for the preparation of high-efficiency material films OLEDs devices.

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“…For efficient light scattering, a sufficiently high refractive index contrast needs to be achieved between the scattering centers and the surrounding polymer. This can be realized using lowindex nanoscaled air voids [22], or high refractive index nanoparticles made of TiO 2 , Al 2 O 3 , or ZrO 2 [21,23,24]. Besides, suitable nanoparticles should have a size comparable to the emitted wavelength to achieve an appropriate scattering cross-section, and thereby to increase the fraction of diffused light, which is referred to as 'haze' in the following.…”

Section: Introductionmentioning

confidence: 99%

Inkjet-printed internal light extraction layers for organic light emitting diodes

Eiselt

Preinfalk

Bittkau

et al. 2018

Flex. Print. Electron.

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We have developed inkjet-printed scattering layers for enhanced light extraction in organic light emitting diodes (OLEDs). These layers are based on scattering polymer/nanoparticle composites, which are prepared from a solvent-free process and used for the outcoupling of waveguide modes to free propagating modes, thus improving the device efficiencies. Two different monomers are examined and an inkjet-printing process is developed for each of them. We first analyze the inks' rheological properties, followed by the optical and morphological properties of the resulting layers. Upon integration of these printed layers into an OLED stack, the device efficiencies are increased by up to 40% with respect to an unpatterned reference device. Furthermore, we show that these internal light extraction layers improve the angular and spectral stability of the devices.

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Light extraction from OLEDs using volumetric light scattering

Cited by 6 publications

References 1 publication

Large-Area Screen-Printed Internal Extraction Layers for Organic Light-Emitting Diodes

Large-Area Screen-Printed Internal Extraction Layers for Organic Light-Emitting Diodes

Research on Organic Light-emitting Diode

Inkjet-printed internal light extraction layers for organic light emitting diodes

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