OLED Encapsulation Structure for Uniform Organic Layer Spreading
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Solution Overview
Problem
During the fabrication of organic light-emitting diode displays, the organic material used in the thin-film encapsulation layer does not spread uniformly, leading to non-uniformity and Mura defects.
Innovation Solution
A three-layer encapsulation structure is implemented, with the second encapsulation layer having an organic material and edges of the first and third encapsulation layers positioned outside the second, and surface roughness differences between areas to control the organic material's spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If organic material having flowability is provided on the substrate, then the organic insulating layer can be formed, but the organic material does not spread uniformly or flows over the substrate
Solution Approach 1:
The patent applies local quality by creating different surface roughness zones within the same encapsulation layer. The first area has a first surface roughness that allows uniform spreading of organic material, while the second area has a second surface roughness that prevents excessive flow. This spatial variation in surface properties enables the organic material to spread uniformly in designated areas without flowing over the substrate boundaries.
Solution Approach 2:
The encapsulation layer is segmented into multiple areas with different surface roughness characteristics. By dividing the encapsulation layer into a first area and a second area, each with controlled surface roughness, the patent enables differentiated control over organic material behavior - uniform spreading in the first area and flow prevention in the second area.
2Reliability
If edges of the first and third encapsulation layers are positioned outside the second encapsulation layer, then the organic material is contained, but the structure complexity increases
Solution Approach 1:
The patent employs a nested structure where the second encapsulation layer containing organic material is positioned between the first and third encapsulation layers. The edges of the first and third layers extend beyond the second layer, creating a nested configuration that physically contains the organic material while maintaining a relatively compact overall structure.
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 structure ensures uniform formation of the organic material and prevents Mura defects, enhancing the display device's quality.
Implementation Method 1
the organic material may not spread uniformly or may flow over the substrate
Implementation Method 2
an organic material having flowability may be provided on a substrate, and the organic material may be cured to form the organic insulating layer
Data Source
AI summary
A display device includes a substrate including a display area and a non-display area surrounding the display area, a plurality of pixels on the substrate in the display area, a first encapsulation layer on the substrate to cover the pixels and including an inorganic material, a second encapsulation layer on the first encapsulation layer and including an organic material, and a third encapsulation layer on the second encapsulation layer and including an inorganic material. An edge of the second encapsulation layer is located in the non-display area, edges of the first encapsulation layer and the third encapsulation layer are located more to an outside than the edge of the second encapsulation layer is. The first encapsulation layer includes a first area and a second area located more to the outside than the first area and having a surface roughness smaller than a surface roughness of the first area.