OLED Thin Film Encapsulation with Scattering Materials
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Solution Overview
Problem
The existing thin film encapsulation techniques in OLED displays lead to significant light reflection and reduced light efficiency due to the alternation of inorganic and organic layers, which prevents light emitted from the organic emission layer from being emitted externally.
Innovation Solution
Incorporating scattering materials with diameters larger than 1/8 of the emitted light wavelength and refractive indices between 1.5 and 3.0 into the thin film encapsulation layer, specifically in organic and inorganic layers, to scatter light and improve transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin film encapsulation layer with alternately layering inorganic layers and organic layers is used to package the OLED, then the OLED is protected from external moisture and oxygen, but light emitted from the organic emission layer is reflected and cannot be emitted to the outside, deteriorating light efficiency
Solution Approach 1:
The patent applies local quality by dispersing scattering materials specifically in the lower organic layer adjacent to the organic light emitting element, rather than uniformly throughout all layers. This localized modification creates a specific region with enhanced light scattering properties where it is most needed, while maintaining the protective encapsulation function of the overall structure.
Solution Approach 2:
The scattering materials act as intermediaries between the organic emission layer and the external environment. These materials with refractive indices between 1.5 and 3.0 mediate the light transmission by scattering light that would otherwise be reflected at the interfaces between layers with different refractive indices, thereby improving light extraction efficiency.
2Loss of energy
If scattering materials with diameters between 100 nm and 500 nm and refractive indices between 1.5 and 3.0 are dispersed in the thin film encapsulation layer, then light efficiency is improved by reducing total reflection, but the device structure becomes more complex
Solution Approach 1:
The patent merges the protective encapsulation function with the light extraction enhancement function by incorporating scattering materials directly into the thin film encapsulation layer structure. This integration allows a single layer to serve dual purposes: protecting the OLED from environmental degradation and improving light extraction efficiency simultaneously.
Solution Approach 2:
The patent employs parameter changes by carefully selecting specific ranges for scattering material properties: diameters between 100 nm and 500 nm, and refractive indices between 1.5 and 3.0. These optimized parameters ensure effective light scattering while maintaining compatibility with the encapsulation layer matrix, achieving improved light efficiency without excessive structural complexity.
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 approach enhances light efficiency by reducing total reflection and increasing light extraction, as demonstrated by improved light extraction efficiency rates for red, green, and blue pixels without altering color coordinates.
Implementation Method 1
one or more scattering materials dispersed in the thin film encapsulation layer
Data Source
AI summary
An organic light-emitting diode (OLED) display according to an exemplary embodiment may include: a substrate and an organic light emitting element on the substrate; a thin film encapsulation layer on the substrate and covering the organic light emitting element; and one or more scattering materials dispersed in the thin film encapsulation layer. According to the exemplary embodiment, light efficiency may be improved by dispersing scattering materials in at least one of an organic layer or an inorganic layer forming a thin film encapsulation layer with a large refractive index difference.