Organic Light Emitting Display Light Extraction Pattern
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Solution Overview
Problem
Organic light emitting display apparatuses face reduced light extraction efficiency and increased power consumption due to light being trapped by total reflection at interfaces, leading to lower brightness and higher power consumption, as well as issues with black visibility and Mura phenomena caused by external light reflection.
Innovation Solution
The introduction of a light extraction pattern with concave and convex portions on the emission area of subpixels, combined with a phase grating portion between the substrate and light extraction pattern, to enhance light extraction efficiency and reduce external light reflection, thereby improving luminance and minimizing rainbow and circular ring Mura.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional planar light extraction structure is used, then the device structure is simple, but light extraction efficiency is reduced due to total reflection at interfaces
Solution Approach 1:
The patent introduces a light extraction pattern with concave and convex portions on the planarization layer surface. The convex portions protrude upward while concave portions recess downward, creating curved interfaces that disrupt total internal reflection pathways. This curvature modification enables more light to escape the organic light emitting layer, directly resolving the contradiction between structural simplicity and light extraction efficiency.
Solution Approach 2:
The invention adds vertical dimensionality to the light extraction interface by creating three-dimensional concave-convex structures on the planarization layer. This transforms a two-dimensional planar surface into a three-dimensional microstructured surface, providing additional light extraction pathways that overcome the limitations of conventional planar structures while maintaining manufacturing feasibility.
2Illumination intensity
If the emission layer operates at high luminance to compensate for low light extraction efficiency, then brightness is improved, but power consumption increases
Solution Approach 1:
The patent converts the previously harmful total internal reflection into a beneficial light extraction mechanism. By designing the concave-convex light extraction pattern, light that would have been trapped by total reflection is now redirected toward the surface and extracted efficiently. This eliminates the need to increase drive current for higher luminance, thereby reducing power consumption while maintaining or improving brightness.
3Ease of manufacture
If a conventional planar structure is used, then manufacturing is simple, but black visibility characteristic deteriorates due to external light reflection
Solution Approach 1:
The concave-convex light extraction pattern creates a microstructured surface that scatters external light incident on the display. The curved interfaces of the concave portions and convex portions disrupt specular reflection pathways, preventing external light from forming coherent reflection patterns. This scattering effect improves black visibility by reducing the intensity of reflected external light while maintaining manufacturing simplicity.
4Device complexity
If light extraction efficiency is low, then device structure remains simple, but brightness is reduced
Solution Approach 1:
The patent segments the planarization layer surface into multiple concave and convex portions, creating a microstructured light extraction pattern. This segmentation divides the light extraction function across multiple discrete features rather than relying on a single planar interface. Each convex portion acts as a light extraction element, collectively enhancing overall brightness while adding only moderate structural complexity that remains compatible with standard manufacturing processes.
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
This solution increases light extraction efficiency, extends the lifetime of the emission layer, reduces power consumption, and achieves real black visibility by minimizing external light reflection, resulting in higher luminance and lower power usage.
Implementation Method 1
a phase grating portion between the substrate and the light extraction pattern to overlap the emission area of each of the plurality of subpixels
Implementation Method 2
since some of the light emitted from the organic emission layer is not emitted to the outside due to total reflection or the like at the interface between the organic light emitting layer and the electrode and/or total reflection at the interface between the substrate and the air layer
Data Source
AI summary
An organic light emitting display apparatus includes a plurality of pixels on a substrate, each including a plurality of subpixels each including an emission area, a planarization layer including a light extraction pattern which is at the emission area of each of the plurality of subpixels and includes a plurality of concave portions and a convex portion surrounding each of the plurality of concave portions, a light emitting device layer on the light extraction pattern, and a phase grating portion between the substrate and the light extraction pattern to overlap the emission area of each of the plurality of subpixels.