OLED Capping Layer Composite Metal Dopant Light Extraction
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Solution Overview
Problem
Existing organic light emitting display devices face issues with poor light extraction efficiency and severe color cast due to the limitations of current capping layer materials, particularly when viewed from different angles.
Innovation Solution
The use of a capping layer with a composite material that includes an organic material and a metal dopant, which enhances the refractive index and light extraction efficiency while minimizing color cast by scattering light in different directions, thereby improving the display's brightness uniformity and reducing color distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the capping layer is made of inorganic material such as LiF, then the device structure is simple, but the refractive index is lower and light extraction efficiency is poor
Solution Approach 1:
The patent applies composite materials by combining organic materials (such as Alq3) with metal dopants (such as Yb, Er, or Tm) to create a capping layer that achieves both high refractive index and effective light scattering. This composite approach resolves the contradiction by integrating the high refractive index property of organic materials with the light scattering capability of metal dopants, thereby improving light extraction efficiency while maintaining manufacturing simplicity.
2Illumination intensity
If the capping layer is made of organic material such as Alq3, then the refractive index and light extraction efficiency are higher, but color cast in the angle of view is more serious
Solution Approach 1:
The patent uses composite materials consisting of organic materials (Alq3) combined with metal dopants (Yb, Er, or Tm). The organic material provides high refractive index for improved light extraction efficiency, while the metal dopants introduce light scattering effects that reduce color cast. This composite structure simultaneously addresses both requirements by leveraging the complementary properties of its constituents.
Solution Approach 2:
The patent applies local quality by incorporating metal dopants at specific concentrations (0.1-10% by weight) within the organic matrix. This localized addition of scattering centers within the capping layer structure enables light scattering to occur at specific regions, effectively reducing color cast while preserving the overall high refractive index and light extraction efficiency of the organic material.
3Object-affected harmful factors
If metal dopant is added to organic material, then light scattering is improved and color cast is reduced, but refractive index may be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of metal dopants within a specific range (0.1-10% by weight). By optimizing this parameter, the patent achieves the right balance between light scattering (color cast reduction) and refractive index maintenance. The controlled doping level ensures sufficient scattering centers to reduce color cast while preventing excessive dopant concentration that would significantly lower the refractive index.
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 proposed solution achieves higher light extraction efficiency and reduced color cast, ensuring uniform brightness and improved viewing angles without the need for additional auxiliary electrodes, thus enhancing the overall performance of the organic light emitting display device.
Implementation Method 1
the metal dopant in the capping layer reflects and refracts the light so that the portion of the light is changed in the propagation direction and is scattered in different directions
Implementation Method 2
the metal dopant in the capping layer reflects and refracts the light so that the portion of the light is changed in the propagation direction and is scattered in different directions
Implementation Method 3
the metal dopant in the capping layer reflects and refracts the light so that the portion of the light is changed in the propagation direction and is scattered in different directions
Data Source
AI summary
An organic light emitting display device and an organic light emitting display apparatus are provided. The organic light emitting display device includes a first electrode and a second electrode disposed opposite to each other, a light emitting layer positioned between the first electrode and the second electrode, and a capping layer positioned on a surface of a side of the second electrode far away from the light emitting layer, the capping layer is formed as a single layer or superposition of a plurality of layers, the at least one layer of the capping layer is a composite layer, and the composite material of the composite layer comprises an organic material and a metal dopant.