Light Extraction Pattern Curvature for OLED Display Luminance
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Solution Overview
Problem
Light emitting display devices face a decrease in luminance and increased power consumption due to low light extraction efficiency, as some emitted light is not externally discharged due to total reflection at interfaces between the light emitting layer and electrodes or the substrate and air layer.
Innovation Solution
A light emitting display apparatus with a substrate featuring a light extraction pattern comprising concave portions and protruding portions on a planarization layer, where at least one concave portion has a curvature of 0.217 μm−1 to 0.311 μm−1, enhancing light extraction efficiency by altering the path of emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planar light emitting structure is used, then the device structure is simple, but light extraction efficiency is low due to total reflection at interfaces
Solution Approach 1:
The patent applies curvature to the light extraction pattern by forming concave portions with specific curvature values (0.217 μm−1 to 0.311 μm−1) on the planarization layer. This curved surface structure modifies the optical path of emitted light, reducing total reflection at interfaces and improving light extraction efficiency while maintaining a relatively simple device structure.
Solution Approach 2:
The patent transitions from a two-dimensional planar surface to a three-dimensional curved surface by forming concave portions with specific depths and curvature. This dimensional change creates additional optical paths for light extraction, allowing light to escape through curved interfaces rather than being trapped by planar total reflection.
2Ease of manufacture
If light extraction efficiency is low, then manufacturing is easier, but luminance decreases and power consumption increases
Solution Approach 1:
The patent optimizes specific parameters of the light extraction pattern, including curvature values (0.217 μm−1 to 0.311 μm−1), depth (50 nm to 500 nm), and pitch (2 μm to 5 μm), to maximize light extraction efficiency. These parameter optimizations improve luminance and reduce power consumption while maintaining compatibility with existing manufacturing processes.
3Device complexity
If light extraction efficiency is low, then device structure is simpler, but power consumption increases
Solution Approach 1:
The curved surface structure of the concave portions improves light extraction efficiency by reducing total reflection, which directly reduces power consumption. This approach achieves energy efficiency without adding complex device structures, as the curvature is formed within the existing planarization layer.
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 improves light extraction efficiency, leading to enhanced luminance and reduced power consumption by effectively redirecting light that would otherwise be trapped, thereby increasing the current efficiency of the display device.
Implementation Method 1
at least one of the plurality of concave portions has a curvature of 0.217 μm−1 to 0.311 μm−1, enhancing light extraction efficiency by altering the path of emitted light
Implementation Method 2
some of the light emitted from a light emitting layer is not externally discharged due to total reflection or the like at an interface between the light emitting layer and an electrode
Data Source
AI summary
A light emitting display apparatus includes a substrate including a plurality of pixels each including an emission area; a light extraction pattern including a plurality of concave portions in the emission area; and a light emitting portion over the light extraction pattern, wherein at least one of the plurality of concave portions has a curvature of 0.217 μm−1 to 0.311 μm−1.