LVT Inorganic Layer for Flexible OLED Encapsulation
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Solution Overview
Problem
Organic light emitting display devices are vulnerable to external environments such as oxygen and moisture, which can lead to oxidization and reduce their lifespan, and there is a demand for slim and flexible display technologies that current encapsulation methods fail to address effectively.
Innovation Solution
A thin-film encapsulating layer is implemented, comprising a moisture absorbing layer with metals like Mg and Ca, and one or more inorganic layers made of low-temperature viscosity transition (LVT) materials like tin oxide, phosphor oxide, and tungsten oxide, which are applied between the organic light-emitting unit and the moisture absorbing layer to prevent oxidization, along with a barrier layer to further protect against moisture and oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional encapsulation structure is used to protect the organic light-emitting unit, then the device is protected from oxygen and moisture, but the device thickness increases and flexibility is reduced
Solution Approach 1:
The patent employs an organic encapsulation layer with thickness of 50-200 nm that is both thin and flexible, replacing conventional thick rigid encapsulation structures. This thin film structure provides sufficient protection against oxidization while maintaining device flexibility and reducing overall thickness, enabling flexible display applications.
Solution Approach 2:
The encapsulation structure uses a composite design combining an organic encapsulation layer (polymer material) with an inorganic layer containing LVT material. This composite structure leverages the flexibility and conformal coverage of organic materials while incorporating the barrier properties of inorganic materials, achieving both thin profile and effective protection.
2Manufacturing precision
If the inorganic layer is deposited at high temperature to ensure proper formation, then the layer quality is improved, but the organic light-emitting unit materials may be damaged
Solution Approach 1:
The patent utilizes the low temperature viscosity transition (LVT) property of the inorganic material, allowing the layer to be deposited at low temperature (below organic material degradation point) and then undergoes a viscosity transition at elevated temperature to achieve proper layer formation and quality without permanently exposing the organic materials to damaging high temperatures.
Solution Approach 2:
The inorganic material undergoes a viscosity transition (phase change) at a specific temperature that is lower than the degradation temperature of organic light-emitting materials. This phase transition enables the material to self-organize and form a high-quality layer at temperatures that do not damage the underlying organic structures.
3Length of moving object
If a thin encapsulation layer is used to reduce device thickness, then flexibility is improved, but the protection against moisture and oxygen may be insufficient
Solution Approach 1:
The encapsulation structure combines organic and inorganic materials with complementary properties. The organic layer provides flexibility and conformal coverage, while the inorganic layer with LVT material provides enhanced barrier properties against moisture and oxygen permeation, achieving effective protection at reduced thickness.
Solution Approach 2:
The patent employs a thin organic encapsulation layer (50-200 nm) that provides sufficient protection through its molecular structure and cross-linking, achieving both thin profile for flexibility and adequate barrier properties through material selection and layer design.
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 solution effectively prevents oxidization of the organic light-emitting unit, enhances the lifespan of the display device, and allows for the development of flexible and slim organic light emitting display apparatuses by creating a robust encapsulation structure that maintains light efficiency and flexibility.
Implementation Method 1
at least one inorganic layer, which is formed on the moisture absorbing layer and includes a low temperature viscosity transition (LVT) inorganic material
Implementation Method 2
a moisture absorbing layer formed on the organic light-emitting unit
Data Source
AI summary
An organic light emitting display apparatus including an organic light-emitting unit formed on a substrate; a moisture absorbing layer formed on the organic light-emitting unit; and at least one inorganic layer, which is formed on the moisture absorbing layer and includes a low temperature viscosity transition (LVT) inorganic material.