Butylene Adhesive Encapsulation Film for Moisture-Stable OLEDs
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Solution Overview
Problem
Organic electronic devices (OEDs), particularly OLEDs, face durability issues due to oxidation from external factors like moisture, requiring effective moisture blocking and reliability under high-temperature and high-humidity conditions during manufacturing and use.
Innovation Solution
A pressure-sensitive adhesive composition incorporating a polymer derived from butylene and a specific monofunctional acrylate compound, along with a multifunctional active energy ray polymerizable compound, is used to form an encapsulation film that maintains excellent processability and heat retention, preventing moisture and oxygen ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyisobutylene (PIB)-based pressure-sensitive adhesive is used for encapsulation, then moisture blocking capability is provided, but processability is low and reliability deteriorates under high-temperature and high-humidity conditions
Solution Approach 1:
The patent modifies the chemical structure of the polymer by introducing specific functional groups (carboxyl, hydroxyl, or amine groups) at controlled concentrations (0.1-10 mmol/g). This parameter change in molecular structure enables the adhesive to maintain both processability and reliability under high-temperature and high-humidity conditions, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent creates a composite adhesive system combining polyisobutylene base polymer with functionalized components containing specific groups. This composite structure provides both the moisture blocking properties of PIB and the enhanced reliability from the functional groups, while maintaining processability through controlled functional group concentration.
2Reliability
If encapsulation is performed to prevent moisture permeation, then durability is improved, but air bubbles are enclosed during lamination and uniform laminating property cannot be obtained
Solution Approach 1:
The patent adjusts the viscosity parameters of the pressure-sensitive adhesive through controlled functional group content and polymer molecular weight. This parameter optimization ensures the adhesive has appropriate flow characteristics for uniform lamination while maintaining encapsulation effectiveness, thus achieving both durability and manufacturing precision.
3Reliability
If the adhesive composition has high viscosity to maintain heat retention, then reliability under high-temperature condition is improved, but processability during panel manufacturing deteriorates
Solution Approach 1:
The patent achieves temperature-dependent viscosity control by incorporating functional groups that provide thermal stability. The adhesive maintains lower viscosity at processing temperatures for good processability, then exhibits higher viscosity and heat retention at operating temperatures, resolving the contradiction between manufacturability and thermal reliability.
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 encapsulation film effectively blocks moisture and oxygen, ensuring the longevity and reliability of OEDs by maintaining excellent moisture blocking properties and heat retention under high-temperature and high-humidity conditions, preventing connection failures and fouling during panel manufacturing.
Implementation Method 1
effectively prevents the permeation of moisture into the OED
Implementation Method 2
a polymer derived from butylene
Data Source
AI summary
An organic electronic device including a substrate, an organic electronic element formed on the substrate, and an encapsulation film encapsulating the organic electronic element. The organic electronic element includes a transparent electrode formed on the substrate, and a light emitting organic material layer formed on the transparent electrode. The light emitting organic material layer includes a hole transport layer, an emitting layer and an electron transport layer. The encapsulation film includes a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes a pressure-sensitive adhesive composition or a crosslinked product thereof. The pressure-sensitive adhesive composition includes a polymer derived from butylene, and has a Mooney viscosity (η*) of 5000 Pa·s to 107 Pa·s measured by a shear stress using a planar jig having a diameter of 8 mm at a strain of 5%, a frequency of 1 Hz and any one temperature point in the range of 30° C. to 150° C.