OLED Scattering Layer for Light Outcoupling
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Solution Overview
Problem
Conventional organic light-emitting diodes (OLEDs) suffer from low light outcoupling efficiency, with only about a quarter of generated light being emitted into the environment, while the rest is lost due to wave guidance and surface plasmons, leading to inefficient light output and aesthetic issues when attempting to enhance outcoupling using scattering films or patterns.
Innovation Solution
An organic light-emitting device with a functional layer stack that includes a scattering layer applied to a carrier layer, comprising organic components with differing refractive indices, which are partially intermixed to form a mesoscopic boundary layer, enhancing light outcoupling by creating refractive index gradients and scattering centers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If scattering films or patterns are applied to increase light outcoupling, then light outcoupling efficiency is improved, but the appearance of the OLED is deteriorated (milky, diffusely reflective surface)
Solution Approach 1:
The patent applies local quality by creating scattering centers only at specific interfaces (e.g., between substrate and underlying layers, or between electrode and adjacent layers) rather than uniformly across the entire surface. This localized scattering approach maintains high outcoupling efficiency while preserving the overall visual appearance of the OLED, avoiding the milky diffuse reflection problem.
Solution Approach 2:
The patent changes the refractive index parameter at specific interfaces by introducing materials with different refractive indices (e.g., inserting an organic layer with refractive index between substrate and electrode, or modifying electrode surface properties). This parameter change creates scattering effects that improve light outcoupling without the aesthetic degradation associated with conventional scattering films.
2Loss of energy
If conventional scattering approaches are used, then light outcoupling is enhanced, but manufacturing complexity increases due to additional films and patterns
Solution Approach 1:
The patent merges the scattering function with existing structural layers in the OLED, such as combining it with the substrate, electrode, or encapsulation layers. By integrating the scattering capability into already-necessary components rather than adding separate scattering films, the manufacturing process complexity is minimized while still achieving improved light outcoupling.
Solution Approach 2:
The patent enables existing layers to serve dual purposes: their primary function (e.g., substrate as structural support, electrode as electrical contact) and an additional scattering function. For example, the substrate or electrode is designed with inherent scattering properties through material selection or surface treatment, eliminating the need for separate scattering components and simplifying manufacturing.
3Stability of the object's composition
If light is guided in substrate and electrodes, then internal light distribution is maintained, but light loss increases due to wave guidance effects
Solution Approach 1:
The patent segments the optical paths by introducing scattering interfaces at specific locations within the device structure. This segmentation breaks up the continuous wave guidance channels in the substrate and electrodes, allowing controlled extraction of guided light at designated points while maintaining light distribution in other regions, thus reducing overall light loss without compromising internal light management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The scattering layer increases light outcoupling efficiency and luminance homogeneity, improving the overall performance and appearance of OLEDs by effectively redirecting guided light, achieving higher light emission compared to conventional devices.
Implementation Method 1
The scattering layer comprises a first organic component and a second organic component with different refractive indices, present in two sublayers
Implementation Method 2
enhancing light outcoupling by creating refractive index gradients and scattering centers
Data Source
AI summary
The invention relates to an organic light-emitting part having a functional layer stack (10), which functional layer stack has a substrate (1), a first electrode (2) above the substrate, an organic functional layer stack (4) above the first electrode, having an organic light-emitting layer (5), and a second electrode (3) above the organic functional layer stack, wherein a layer (1, 2, 3) of the functional layer stack (10) forms a carrier layer (6) for a diffusion layer (7), wherein the diffusion layer (7) has at least one first and one second organic component (71, 72) having indices of refraction that differ from each other, wherein the first organic component (71) is hydrophobic and the second organic component (72) is hydrophilic, wherein the glass transition temperature of a mixture of the first organic component (71) and the second organic component (72); lies above the room temperature and wherein the first organic component (71) and the second organic component (72) are partially segregated in the diffusion layer (7) and the diffusion layer (7) has a mesoscopic boundary layer (75) between the first and second organic components (71, 72) or the diffusion layer (7) is present as a mesophase (78) having the first and second organic component (71, 72). The invention further relates to a method for producing an organic light-emitting part.