OLED Light Extraction Layer Stack for Refractive Index Matching
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Solution Overview
Problem
Existing display technologies face low light extraction efficiency due to mismatched refractive indices of film layers and energy loss at the interface of electrodes and organic materials in OLED display panels.
Innovation Solution
A display panel design featuring a light extraction layer assembly with a stacked arrangement of primary and secondary extraction layers, where the primary extraction layer has a higher refractive index than the secondary extraction layer, and a barrier layer with a refractive index smaller than the secondary extraction layer, optimized to enhance light extraction efficiency by matching refractive indices and reducing total reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single light extraction layer is used, then the device complexity is low, but the light extraction efficiency is insufficient
Solution Approach 1:
The light extraction layer is divided into multiple sub-layers (first light extraction layer, second light extraction layer, third light extraction layer) with different refractive indices. Each sub-layer segment performs a specific function in the light extraction process, collectively improving overall extraction efficiency while managing complexity through functional segmentation.
Solution Approach 2:
The patent employs a composite light extraction layer structure combining materials with different refractive indices (n1, n2, n3 where n1>n2>n3). This composite approach allows optimization of light extraction by creating refractive index gradients that reduce total internal reflection and improve outcoupling efficiency.
2Loss of energy
If the refractive index of the light extraction layer is increased, then the light extraction efficiency is improved, but the total reflection at interfaces increases
Solution Approach 1:
Different regions of the light extraction layer are assigned different refractive indices tailored to local requirements. The first light extraction layer (higher n1) is positioned where maximum extraction is needed, while subsequent layers (lower n2, n3) gradually reduce reflection at interfaces by creating a refractive index gradient that matches to the underlying layers.
Solution Approach 2:
The patent systematically varies the refractive index parameter across multiple layers (n1>n2>n3) to optimize light extraction. By changing this physical parameter in a controlled gradient manner, the structure reduces abrupt refractive index mismatches that cause total internal reflection, thereby improving overall extraction efficiency.
3Loss of energy
If multiple secondary extraction layers are added, then the light extraction efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The complex light extraction function is segmented across multiple layers with progressively lower refractive indices. This segmentation allows each layer to be optimized independently for its specific thickness and material properties, making the overall system more manufacturable despite the increased number of layers.
Solution Approach 2:
The patent employs systematic parameter changes in refractive index across layers (n1>n2>n3) to create a gradient structure. This gradual parameter transition reduces sensitivity to precise thickness variations, as the refractive index gradient provides a buffer against manufacturing tolerances, thereby improving manufacturability.
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 multi-layer structure improves light extraction efficiency and output effect by increasing optical interference and reducing energy loss, resulting in enhanced light extraction and emission direction control.
Implementation Method 1
the light extraction layer assembly comprises at least two light extraction layers in a stacked arrangement, the at least two light extraction layers comprise a primary extraction layer and at least one secondary extraction layer, the primary extraction layer has a refractive index greater than that of the secondary extraction layer
Implementation Method 2
The multi-layer structure improves light extraction efficiency and output effect by increasing optical interference and reducing energy loss
Data Source
AI summary
A display panel, a display module and a display device. The display panel includes: a substrate in a stacked arrangement, a light-emitting device layer, a light extraction layer assembly, and a barrier layer; wherein the light extraction layer assembly includes at least two light extraction layers in a stacked arrangement, the at least two light extraction layers including a primary extraction layer and at least one secondary extraction layer disposed on one side of the primary extraction layer or on two opposite sides of the primary extraction layer, and the primary extraction layer has a refractive index greater than that of the secondary extraction layer; and the secondary extraction layer has a refractive index greater than that of the barrier layer.