Multilayer Adhesive for Organic Electronic Device Encapsulation

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Solution Overview

Problem

Organic electronic devices (OEDs), particularly OLEDs, face durability issues due to sensitivity to moisture and oxygen, leading to oxidation and damage from external factors, with existing encapsulation methods either increasing device thickness, being vulnerable to physical impacts, or having inadequate moisture absorption capacity.

Innovation Solution

A multilayer adhesive structure with a curable resin and moisture absorbent, where the absorbent is distributed in two regions, one in contact with the OED and one not, with controlled concentrations to prevent volume expansion and chemical reactions, ensuring effective moisture barrier properties while minimizing physical and chemical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional airtight container with internal space is used for encapsulation, then moisture protection is provided, but device thickness increases and vulnerability to physical impacts occurs

Engineering Contradiction:

Improvemoisture protectionVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The invention extracts the moisture absorption function from a separate container structure and integrates it directly into the encapsulation adhesive layer. The adhesive contains moisture-absorbing particles dispersed within the resin matrix, eliminating the need for a dedicated airtight container with internal space, thereby reducing device thickness while maintaining moisture protection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges multiple functions into the encapsulation adhesive: structural bonding, moisture barrier, and moisture absorption. By incorporating moisture-absorbing particles directly into the adhesive composition, the system combines the protective functions of encapsulation and dehumidification into a single integrated layer, eliminating the need for separate container structures.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a desiccant layer with solid particles is used for moisture absorption, then moisture absorption capacity is provided, but insufficient absorption performance and chemical damage to device layers occur

Engineering Contradiction:

Improvemoisture absorption capacityVSAvoidchemical damage to device layers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention applies local quality by positioning moisture-absorbing particles specifically within the adhesive layer where moisture ingress occurs first. This localized placement ensures that moisture is absorbed at the boundary before reaching sensitive device layers, providing effective protection while using minimal amounts of moisture-absorbing material.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The adhesive resin acts as an intermediary between the external environment and the device layers. The moisture-absorbing particles embedded in the resin capture moisture through the adhesive matrix, preventing direct contact between moisture and sensitive device components like the cathode and passivation layer, thereby avoiding chemical damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If metal oxide is used as moisture absorbent, then moisture absorption is achieved, but volume expansion and chemical reactions cause physical damage to device

Engineering Contradiction:

Improvemoisture absorptionVSAvoiddevice structural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention changes the material parameters by selecting moisture-absorbing particles with low volume expansion characteristics and chemically inert properties. These modified material parameters ensure that moisture absorption occurs without significant volume change or harmful chemical reactions, preserving the structural integrity of the encapsulated device.

Inventive Principle:

Principle #35Parameter changes

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 effectively prevents moisture and oxygen penetration, enhancing the durability and reliability of OEDs by maintaining a low water vapor transmission rate and reducing physical and chemical damage, thus improving the lifespan of the devices.

Implementation Method 1

a moisture absorbent is present at contents of 0 to 20% and 80 to 100% in the first and second regions, respectively, based on the total weight of the moisture absorbent in the adhesive

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

the adhesive effectively prevents moisture and oxygen penetration, enhancing the durability and reliability of OEDs by maintaining a low water vapor transmission rate

Methodology Applied

Scientific EffectPermeation barrier: Permeation

Data Source

PatentUS11142669B2Adhesive and method of encapsulating organic electronic device using the same

Publication Date: 2021.10.12 LG CHEM LTD

AI summary

An adhesive, and an encapsulated product and method of encapsulating an organic electronic device (OED) using the same are provided. The adhesive film serves to encapsulate the OED and includes a curable resin and a moisture absorbent, and the adhesive includes a first region coming in contact with the OED upon encapsulation of the OED and a second region not coming in contact with the OED. Also, the moisture absorbent is present at contents of 0 to 20% and 80 to 100% in the first and second regions, respectively, based on the total weight of the moisture absorbent in the adhesive.