Radiation Extraction Layer Microstructuring for OLED Directional Control
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Solution Overview
Problem
Radiation-emitting devices, such as OLEDs, typically exhibit a Lambertian radiation profile, which is not suitable for lighting applications, as it lacks directional control and efficiency, leading to unwanted reflections and reduced output.
Innovation Solution
A radiation-emitting device with a radiation extraction layer featuring regularly arranged geometric structural elements on one side, which scatters and refracts radiation, breaking the Lambertian profile and enhancing output efficiency by reducing total reflection and improving radiation distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a radiation extraction layer with regular microstructuring is used, then the radiation power coupled out is increased and the radiation profile becomes directional, but the manufacturing complexity increases due to the need for precise geometric structural elements
Solution Approach 1:
The radiation extraction layer is segmented into multiple functional zones: a first region with geometric structural elements for refraction and directional control, and a second region with scattering centers for homogeneous radiation distribution. This segmentation allows each zone to perform its specific function optimally while working together to resolve the contradiction between increasing radiation power and managing device complexity.
Solution Approach 2:
Different regions of the radiation extraction layer are assigned different local properties: the first region has geometric structural elements (lenses, prisms, or pyramids) for refraction and directional radiation control, while the second region contains scattering centers for homogenizing radiation distribution. This local differentiation enables the device to achieve both high radiation power and controlled radiation profile without requiring the entire structure to be highly complex.
2Stability of the object's composition
If scattering regions are added to the radiation extraction layer, then the radiation distribution becomes more homogeneous and total reflection is reduced, but the device complexity increases
Solution Approach 1:
The patent merges two previously separate components (radiation extraction layer and scattering layer) into a single integrated radiation extraction layer with multiple functional regions. The scattering centers are incorporated within the same layer that contains the geometric structural elements, eliminating the need for separate layers and reducing overall device complexity while achieving homogeneous radiation distribution.
Solution Approach 2:
The radiation extraction layer is designed as a multi-functional component that simultaneously performs radiation extraction, directional control through refraction, and homogeneous distribution through scattering. By combining these functions in a single layer with different functional regions, the patent reduces device complexity compared to using separate layers for each function.
3Illumination intensity
If geometric structural elements are used for refraction, then the radiation profile deviates from Lambertian and intensity increases at specific angles, but the surface becomes more matt and color dependence on observation angle increases
Solution Approach 1:
The patent introduces asymmetry in the form of geometric structural elements (lenses, prisms, or pyramids) with specific orientations and shapes that refract radiation in preferred directions. These asymmetric structures create directional radiation profiles with enhanced intensity at specific viewing angles, resolving the contradiction between achieving high intensity and maintaining surface finish quality.
4Power
If the radiation extraction layer is made completely transparent to avoid intensity losses, then the radiation power is maximized, but the ability to control and scatter radiation is reduced
Solution Approach 1:
The radiation extraction layer exhibits local quality variations: certain regions are designed to be completely transparent for maximum radiation transmission, while other regions contain scattering centers for radiation control and homogenization. This spatial differentiation of optical properties allows the device to simultaneously maximize radiation power and provide versatile radiation control capabilities.
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 solution increases the coupled-out radiation power and intensity, particularly at specific viewing angles, while reducing color dependence on observation angle and surface roughness, resulting in improved luminance and efficacy.
Implementation Method 1
By microstructuring the side of the radiation extraction layer facing away from the active layer with regularly arranged geometric structural elements, a refraction of the radiation striking the interface (in particular a refraction of light) occurs at the interface to the surrounding medium.
Implementation Method 2
The radiation extraction layer is further characterized in that it contains, at least in some areas, regions which cause the radiation (in particular the primary radiation) to be scattered.
Data Source
Figure 1
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Figure 4~4A
AI summary
The invention relates to a radiation-emitting device comprising an organic radiation-emitting functional layer and a radiation ejection layer. The organic radiation-emitting functional layer emits a primary radiation; the radiation ejection layer is arranged in the beam path of the primary radiation. On the side facing away from the radiation-emitting functional layer, the radiation ejection layer has a microstructure having regularly arranged geometric structural elements; at least some areas of the radiation ejection layer contain regions that cause scattering of the primary radiation.