Thin Film Encapsulation for Flexible OLED Stress Relief
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Solution Overview
Problem
Organic light-emitting display devices are vulnerable to external agents like oxygen and moisture, and there is a need for a strong and thin encapsulation structure to enhance their durability and longevity, particularly for developing flexible and thin organic light-emitting displays.
Innovation Solution
A thin film encapsulation structure is created using a combination of elastic and inorganic layers, where a transparent elastomer and low temperature viscosity transition inorganic material, such as tin oxide, are used, with an adhesion promoting layer to reduce stress and improve sealing, and an additional elastic layer and inorganic film are added to further enhance the encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a robust encapsulation structure is used to protect against external agents, then reliability is improved, but device thickness increases
Solution Approach 1:
The encapsulation structure is divided into multiple thin alternating layers of inorganic material (e.g., aluminum oxide, titanium oxide) and organic material (e.g., polyimide). This segmentation allows each layer to be very thin while the composite structure provides robust protection against oxygen and moisture penetration.
Solution Approach 2:
The patent uses composite encapsulation structures combining inorganic and organic layers. The inorganic layers provide barrier properties against external agents, while the organic layers provide flexibility and stress relief, achieving both protection and thinness.
2Reliability
If a robust encapsulation structure is used to protect against external agents, then reliability is improved, but device flexibility is reduced
Solution Approach 1:
The organic layers in the encapsulation structure (e.g., polyimide) provide flexibility and can accommodate bending of the display device. These flexible organic layers are interleaved with inorganic barrier layers, maintaining protection while enabling flexibility.
Solution Approach 2:
The encapsulation structure is designed to be dynamic and adaptable to mechanical deformation. The organic layers can stretch and bend with the device, while the inorganic layers provide the necessary barrier function, allowing the structure to maintain integrity during flexing.
3Reliability
If multiple film layers are stacked to improve encapsulation, then protection is improved, but stress between layers increases
Solution Approach 1:
The patent controls the thickness parameters of each layer to optimize stress distribution. By carefully selecting the thickness of inorganic and organic layers, the structure achieves effective encapsulation while minimizing cumulative stress and preventing delamination between layers.
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 effectively seals the organic light-emitting display device from external agents, reducing stress and improving the lifespan and flexibility of the device, while maintaining a thin and strong encapsulation.
Implementation Method 1
a first inorganic film that is formed on the first elastic layer and includes a low temperature viscosity transition (LVT) inorganic material
Implementation Method 2
a first elastic layer that is formed on the organic film and includes an elastomer
Data Source
AI summary
An organic light-emitting display device includes: a substrate; an organic light-emitting unit that is formed on the substrate and comprises a first electrode, an intermediate layer, and a second electrode; an organic film formed on the organic light-emitting unit; a first elastic layer that is formed on the organic film and comprises an elastomer; and a first inorganic film that is formed on the first elastic layer and comprises a low temperature viscosity transition (LVT) inorganic material.