Quantitative allocation of Bragg scattering effects in highly efficient OLEDs fabricated on periodically corrugated substrates

Fuchs, Cornelius; Schwab, Tobias; Roch, Teja; Eckardt, S.; Lasagni, Andrés Fabían; Hofmann, Simone; Lüssem, Björn; Müller‐Meskamp, Lars; Leo, Karl; Gather, Malte C.; Scholz, Reinhard

doi:10.1364/oe.21.016319

Cited by 44 publications

(31 citation statements)

References 37 publications

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“…Figure 5 shows mode profiles of the lowest-order waveguided and plasmonic mode supported by a standard bottom-emitting OLED stack and how these modes can interact with a scattering structure located underneath the anode of the device. [58][59][60] However, in general, these photonic structures are wavelength selective, which is why they are difficult to apply in broadband white OLEDs. 40 and 55) and PEDOT/PSS anodes.…”

Section: Wavelength-independent Scattering-based Outcoupling Approachesmentioning

confidence: 99%

Recent advances in light outcoupling from white organic light-emitting diodes

2015

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Organic light-emitting diodes (OLEDs) have been successfully introduced to the smartphone display market and have geared up to become contenders for applications in general illumination where they promise to combine efficient generation of white light with excellent color quality, glare-free illumination, and highly attractive designs. Device efficiency is the key requirement for such white OLEDs, not only from a sustainability perspective, but also because at the high brightness required for general illumination, losses lead to heating and may, thus, cause rapid device degradation. The efficiency of white OLEDs increased tremendously over the past two decades, and internal charge-to-photon conversion can now be achieved at ∼100% yield. However, the extraction of photons remains rather inefficient (typically <30%). Here, we provide an introduction to the underlying physics of outcoupling in white OLEDs and review recent progress toward making light extraction more efficient. We describe how structures that scatter, refract, or diffract light can be attached to the outside of white OLEDs (external outcoupling) or can be integrated close to the active layers of the device (internal outcoupling). Moreover, the prospects of using top-emitting metal-metal microcavity designs for white OLEDs and of tuning the average orientation of the emissive molecules within the OLED are discussed.

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Section: Wavelength-independent Scattering-based Outcoupling Approachesmentioning

confidence: 99%

Recent advances in light outcoupling from white organic light-emitting diodes

2015

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“…Because losses are so high, there is a lot of potential for improvement. A plurality of solutions have been proposed to increase OLED efficiency, such as high-index substrates [3], grating-assisted outcoupling [4][5][6] and many others [7]. We refer to the work of Brütting et al [8] for an overview.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic materials in OLEDs for high outcoupling efficiency

2015

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Abstract:We present the results of an optical study in which we evaluate the effect of anisotropic electron transport layers (ETL) and anisotropic hole transport layers (HTL) on the outcoupling efficiency of bottom emitting organic light emitting diodes (OLEDs). We demonstrate that optical anisotropy can have a profound influence on the outcoupling efficiency and introduce a number of design rules which ensure that light extraction is enhanced by anisotropic layers.

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“…Since laser beams can be focused by optical lenses on minimal spot sizes of ~5 µm, another way of concentrating the light source has to be found. A solution to this problem is presented by a new way of laser interference technology 15,16 .…”

Section: Metallic Thin Films As Transparent High Performance Electrodesmentioning

confidence: 99%

Fabrication of highly efficient transparent metal thin film electrodes using Direct Laser Interference Patterning

Eckhardt

Müller‐Meskamp

Loeser

et al. 2015

Laser-Based Micro- And Nanoprocessing IX

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The demand of highly efficient transparent electrodes without the use of rare earth materials such as indium requires a new generation of thin metallic films with both high transparency and electrical conductivity. For this purpose, Direct Laser Interference Patterning was used to fabricate periodic hole-like surface patterns on thin metallic films in order to improve their optical transparency by selective laser ablation of the material and at the same time keeping the electrical properties at an acceptable level. Metallic films consisting of aluminum and copper with film thicknesses ranging between 5 and 40 nm were deposited on glass substrates and treated with nanosecond and picosecond pulse laser system. In order to analyze the processability of the films, the laser ablation threshold for each material as function of the layer thickness and pulse duration was firstly determined. After analyzing these initial experiments, the samples were structured with a 1.7 µm spatial period hole-like-pattern using three beam direct laser interference patterning. The structural quality of the fabricated structures was analyzed as function laser energy density (laser fluence) using scanning electron microscopy (SEM), atom force microscopy (AFM). Finally, optical and electrical properties of the films were characterized using optical spectroscopy, as well as surface impedance measurements.

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Quantitative allocation of Bragg scattering effects in highly efficient OLEDs fabricated on periodically corrugated substrates

Cited by 44 publications

References 37 publications

Recent advances in light outcoupling from white organic light-emitting diodes

Recent advances in light outcoupling from white organic light-emitting diodes

Anisotropic materials in OLEDs for high outcoupling efficiency

Fabrication of highly efficient transparent metal thin film electrodes using Direct Laser Interference Patterning

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