Electroluminescent Display Light Extraction Pattern
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Solution Overview
Problem
The light extraction efficiency of electroluminescent display devices is degraded due to a significant portion of emitted light being trapped within the device, primarily due to surface plasmon components and optical waveguide modes, leading to reduced out-coupling efficiency.
Innovation Solution
The implementation of an electroluminescent display device with an overcoat layer featuring a plurality of holes and connecting portions on the first electrode, along with a light extraction pattern in the holes, enhances light extraction by allowing trapped light to be re-reflected and extracted through inclined surfaces, thereby improving the light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light is emitted from the emitting layer, then light output is generated, but most light (60-70%) is trapped due to surface plasmon components and optical waveguide modes, degrading light extraction efficiency
Solution Approach 1:
The first electrode is divided into multiple holes that expose the overcoat layer, segmenting the electrode structure to create multiple light extraction pathways. This segmentation allows trapped light to escape through the holes while maintaining the electrode's conductivity function through the connecting portions between holes.
Solution Approach 2:
The invention introduces a vertical dimension by creating holes through the first electrode to expose the overcoat layer, transforming the light extraction from a planar interface to a three-dimensional structure with multiple extraction planes and angles.
2Loss of energy
If a conventional flat electrode structure is used, then device simplicity is maintained, but light extraction efficiency is degraded due to trapped light
Solution Approach 1:
The first electrode is segmented into multiple holes with connecting portions, creating a patterned structure that improves light extraction while maintaining manufacturing feasibility through standard photolithography processes.
Solution Approach 2:
The electrode structure is modified locally at specific regions to create holes that expose the overcoat layer, while other regions maintain the continuous electrode structure. This local modification approach improves light extraction efficiency without completely redesigning the entire electrode system.
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 configuration effectively increases the light extraction efficiency by re-directing trapped light out of the device, reducing the appearance of black areas and enhancing overall display performance.
Implementation Method 1
light extraction pattern in at least one of the plurality of holes and on the overcoat layer... allowing trapped light to be re-reflected and extracted through inclined surfaces
Data Source
AI summary
A light extraction pattern is disposed in each hole of a first electrode, or a first electrode including round portions and pattern portions is disposed so that light trapped in an emission layer can be output uniformly. In this way, the light extraction efficiency can be effectively improved, and occurrence of a black area can be prevented.