Dual-Sealant Encapsulation for OLED Moisture Protection
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Solution Overview
Problem
Organic electro-luminescence display devices are susceptible to moisture and oxygen, leading to dark spots and reduced reliability, especially in high-temperature high-humidity environments, which affects their lifetime.
Innovation Solution
The use of a dual-sealant approach with a UV-curable resin as the first sealant and frit glass as the second sealant, where the frit glass provides excellent moisture tolerance and adhesion, protecting the organic electro-luminescent diode from external moisture and oxygen, and the first sealant acts as a barrier to prevent outgassing damage during the curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sealant material is used to attach substrates, then the device structure is simple, but the protection against moisture and oxygen is insufficient leading to dark spots and reduced reliability
Solution Approach 1:
The encapsulation structure is divided into two distinct sealant layers: a first sealant material positioned around the thin film transistor and organic electro-luminescence diode, and a second sealant material positioned around the outer perimeter of the first sealant material. This segmentation provides enhanced protection against moisture and oxygen penetration while maintaining structural integrity
Solution Approach 2:
The patent employs composite sealing by combining two different sealant materials with complementary properties. The first sealant material provides initial sealing and positioning, while the second sealant material provides additional environmental protection and structural support, creating a composite encapsulation system that overcomes the limitations of single-material sealing
2Manufacturing precision
If substrates are attached without precise alignment, then the alignment process is simple and quick, but the thin film transistor and organic electro-luminescence diode cannot be in close proximity affecting device performance
Solution Approach 1:
Alignment marks are formed on both the first and second substrates before the bonding process. These pre-formed alignment marks guide the precise positioning of substrates during attachment, ensuring that the thin film transistor and organic electro-luminescence diode are in close proximity without requiring complex real-time alignment procedures
Solution Approach 2:
The alignment marks serve as intermediary reference features that facilitate precise substrate alignment. By providing visible or detectable reference points on both substrates, the alignment marks enable accurate positioning during the bonding process while simplifying the overall alignment procedure
3Reliability
If the first sealant material is cured without protection, then the curing process is simple and fast, but outgassing during curing damages the organic electro-luminescence diode
Solution Approach 1:
A protective layer is formed over the organic electro-luminescence diode before the curing process. This protective layer acts in advance to prevent damage from outgassing that will occur during subsequent curing of the first sealant material, blocking harmful gases from reaching and damaging the sensitive diode structure
Solution Approach 2:
The protective layer serves as a cushioning barrier positioned beforehand to absorb or deflect the harmful effects of outgassing during the curing process. This pre-positioned protection ensures that even if outgassing occurs, the organic electro-luminescence diode remains shielded from damage
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 method significantly enhances the lifetime and reliability of the organic electro-luminescence display device by effectively sealing the diode and preventing damage from moisture and oxygen, while also reducing defects and improving production yield.
Implementation Method 1
A first sealant material which is a UV-curable resin is positioned around the thin film transistor and the organic electro-luminescence diode
Implementation Method 2
a second sealant material which is frit glass is positioned around an outer perimeter of the first sealant material
Data Source
AI summary
An organic electro-luminescence display device includes a thin film transistor on a first substrate, where the thin film transistor has a drain region and a common electrode connected to the drain region. An organic electro-luminescence diode resides on a second substrate, where the organic electro-luminescence diode includes a spacer covered with a diode electrode. First and second sealant materials reside at a periphery of the first and second substrates, where the first sealant material surrounds the thin film transistor and the organic electro-luminescence diode, and the second sealant material surrounds an outer perimeter of the first sealant material. The first and second substrates are bonded together, such that the common electrode of the thin film transistor contacts the diode electrode of the organic electro-luminescence diode. The bonding process is carried out by sequentially sealing the first sealant material and the second sealant material.