Adhesive Composition for OLED Encapsulation
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Solution Overview
Problem
Organic electronic devices (OEDs), particularly OLEDs, are sensitive to moisture and oxygen, leading to durability issues due to external factors like humidity, and existing adhesive compositions lack reliability and processability under high-temperature and high-humidity conditions.
Innovation Solution
An adhesive composition comprising an olefin-based resin with a low water vapor transmission rate, combined with a heat-curable resin and a photocurable compound, is applied to encapsulate OEDs, using a double curing method to control fluidity and maintain shape, ensuring excellent moisture barrier properties and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polyisobutylene-based pressure-sensitive adhesive is used for encapsulation, then the adhesive can be applied easily, but it shows low reliability under high-temperature and high-humidity conditions and lacks high processability
Solution Approach 1:
The patent uses a composite adhesive composition containing polyisobutylene resin as the base adhesive, combined with a specific rubber component (styrene-butadiene rubber or nitrile rubber) and a crosslinking agent. This composite structure maintains the ease of application of pressure-sensitive adhesive while adding reliability under harsh conditions through the crosslinked network formed by the rubber and crosslinking agent.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the adhesive by controlling the molecular weight of polyisobutylene (10,000-1,000,000), the content of rubber component (1-50 parts by weight per 100 parts of polyisobutylene), and the type of crosslinking agent. These parameter changes enable the adhesive to maintain stability and reliability under high-temperature and high-humidity conditions while preserving ease of application.
2Ease of manufacture
If an adhesive composition with high fluidity is used for coating, then the coating process is simple, but it is difficult to maintain a desired capsulated shape after coating
Solution Approach 1:
The patent applies the adhesive composition in a liquid state for easy coating, then performs a preliminary curing action by irradiating with ultraviolet light (wavelength 300-400 nm, dose 1-10 J/cm²) before final heat curing. This preliminary action partially sets the adhesive to maintain the desired capsulated shape while allowing the coating process to remain simple.
Solution Approach 2:
The patent employs a two-stage curing process: first ultraviolet light curing (period 1) to initially set the adhesive and maintain shape, then heat curing at 60-100°C for 1-24 hours (period 2) to complete the curing. This periodic action sequence ensures both ease of coating and shape maintenance.
3Duration of action of stationary object
If conventional adhesive compositions are used for encapsulation, then the encapsulation structure can be formed, but they exhibit poor moisture barrier properties and low durability under high-temperature and high-humidity conditions
Solution Approach 1:
The patent creates a composite adhesive system combining polyisobutylene resin with rubber components (styrene-butadiene rubber or nitrile rubber) and crosslinking agents (isocyanate, epoxy, or carboxyl groups). This composite structure provides both encapsulation formation and superior moisture barrier properties with enhanced durability under high-temperature and high-humidity conditions.
Solution Approach 2:
The patent enhances specific local properties of the adhesive by incorporating rubber components with specific molecular weights and crosslinking agents with particular functional groups. The crosslinking density and distribution are controlled to provide localized moisture barrier enhancement and durability improvement in the encapsulation structure.
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 adhesive composition effectively blocks moisture and oxygen, enhancing the lifespan of OEDs by providing a reliable and durable encapsulation structure even at high temperatures and humidity levels, ensuring the longevity of OLEDs and other organic electronic devices.
Implementation Method 1
the applied adhesive composition may be precured by light irradiation to control fluidity
Implementation Method 2
an adhesive composition, which can form an encapsulation structure effectively blocking moisture or oxygen flowing into an OED from the outside
Data Source
Figure 1
AI summary
Provided are an adhesive composition and an organic electronic device (OED) including the same, and particularly, an adhesive composition, which may form an encapsulation structure effectively blocking moisture or oxygen flowing into an OED from the outside, thereby ensuring the lifespan of the OED, realize a top-emission OED, and exhibit excellent adhesive durability and reliability, and an OED including the same.