Variable Thickness Encapsulation for OLED Water Permeation
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Solution Overview
Problem
Organic light emitting display devices face issues with water permeation through the adhesive layer, leading to degradation of the organic light emitting diode layer and increased likelihood of cracks due to physical damage, as well as delamination between the organic light emitting layer and the cathode electrode, particularly in flexible displays.
Innovation Solution
The solution involves an organic light emitting display device design where the encapsulation substrate is formed to be thicker outside the active area than within, and the adhesive layer is made thicker within the active area, with a cover layer added to prevent water permeation and distribute tensile forces more evenly, thereby reducing the risk of delamination and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the adhesive layer is made thinner to prevent water permeation, then water resistance is improved, but crack resistance deteriorates
Solution Approach 1:
The adhesive layer is designed with different thicknesses in different regions: thinner in the active area to prevent water permeation, and thicker in the non-active area to prevent cracks from external impacts. This local variation in thickness allows simultaneous optimization of both water resistance and mechanical strength.
2Object-affected harmful factors
If the encapsulation substrate is made thicker to prevent water permeation, then water resistance is improved, but delamination risk increases
Solution Approach 1:
The encapsulation substrate is designed with different thicknesses in different regions: thicker in the non-active area to prevent water permeation, and thinner in the active area to reduce tensile force and prevent delamination. This local variation allows simultaneous optimization of water resistance and delamination resistance.
Solution Approach 2:
The encapsulation substrate is divided into two distinct regions with different thicknesses: a first region (active area) and a second region (non-active area). This segmentation allows each region to be optimized for its specific function while working together as a unified structure.
3Strength
If the adhesive layer is made thicker to prevent cracks, then crack resistance is improved, but water permeation increases
Solution Approach 1:
The adhesive layer is designed with different thicknesses in different regions: thicker in the non-active area to prevent cracks from external impacts, and thinner in the active area to prevent water permeation. This local variation in thickness allows simultaneous optimization of both mechanical strength and water resistance.
4Reliability
If the encapsulation substrate is made thinner to prevent delamination, then delamination resistance is improved, but water permeation increases
Solution Approach 1:
The encapsulation substrate is designed with different thicknesses in different regions: thinner in the active area to reduce tensile force and prevent delamination, and thicker in the non-active area to prevent water permeation. This local variation allows simultaneous optimization of both delamination resistance and water resistance.
Data Source
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AI summary
An organic light emitting display device is discussed. The organic light emitting display device according to an embodiment includes an organic light emitting diode layer provided at an active area of a base substrate; an encapsulation layer encapsulating the organic light emitting diode layer to protect the organic light emitting diode layer; an adhesive layer in the encapsulation layer and provided on the organic light emitting diode layer to cover upper and side surfaces of the organic light emitting diode layer; and an encapsulation substrate in the encapsulation layer and provided on the adhesive layer. The encapsulation substrate is provided to have different thicknesses at the active area and outside the active area.