Organic Light-Emitting Display Encapsulation for Light Extraction
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Solution Overview
Problem
Existing organic light emitting displays (OLEDs) face challenges in achieving optimal luminance due to mismatched refractive indices of layers, which affect light extraction efficiency and overall display performance.
Innovation Solution
The OLEDs incorporate a specific multilayer encapsulation structure with carefully controlled refractive indices in the encapsulation layer, comprising sub-inorganic layers with varying thicknesses and refractive indices to optimize light transmission and extraction, including a first sub-inorganic layer of 5000 Å or more and a second sub-inorganic layer of 3000 Å or less, with a refractive index difference of 0.09 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer encapsulation structure is used, then the device structure is simple, but the light extraction efficiency is insufficient due to refractive index mismatch
Solution Approach 1:
The encapsulation layer is divided into multiple sub-layers (first sub-inorganic layer, second sub-inorganic layer, organic layer, third sub-inorganic layer) with different refractive indices. This segmentation allows each layer to contribute differently to light extraction, with the first and second sub-inorganic layers having refractive indices of 1.7-1.9 and 1.4-1.6 respectively, creating optimal refraction conditions to improve luminance without excessive complexity.
2Illumination intensity
If the thickness of the encapsulation layer is increased, then light extraction efficiency may improve, but the device becomes thicker and more complex
Solution Approach 1:
Different regions of the encapsulation structure are assigned different thicknesses and materials optimized for their specific functions. The first sub-inorganic layer has thickness of 5000 Å or more for optimal refraction, while the second sub-inorganic layer has thickness of 3000 Å or less. This local optimization allows effective light extraction without uniformly increasing the overall device thickness.
3Illumination intensity
If layers with different refractive indices are used, then light extraction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for refractive indices (first sub-inorganic layer: 1.7-1.9, second sub-inorganic layer: 1.4-1.6) and thicknesses (first layer: 5000 Å or more, second layer: 3000 Å or less) to optimize light extraction. By defining these parameters within specific ranges rather than fixed values, the design accommodates manufacturing variations while maintaining effective light extraction performance.
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 design enhances luminance by improving light extraction and overall display performance, resulting in improved brightness and efficiency of the OLEDs.
Implementation Method 1
the encapsulation layer includes a first sub-inorganic layer on the organic light emitting diodes; a second sub-inorganic layer on the first sub-inorganic layer and having a refractive index different from a refractive index of the first sub-inorganic layer
Data Source
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AI summary
An organic light emitting display (1) is provided. The organic light emitting display includes a first base substrate (101); a plurality of organic light emitting diodes disposed on the first base substrate; an encapsulation layer disposed on the organic light emitting diodes (310); and a plurality of first color conversion filters (531, 532, 533) disposed on the encapsulation layer. The encapsulation layer includes: a first sub-inorganic layer (412) disposed on the organic light emitting diodes; a second sub-inorganic layer (413) disposed on the first sub-inorganic layer and having a refractive index different from that of the first sub-inorganic layer; an organic layer (420) disposed on the second sub-inorganic layer; and a third sub-inorganic layer (432) disposed on the organic layer.