Multilayer Sealing Structure for OLED Dark Spot Prevention

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Solution Overview

Problem

In organic light emitting devices, the generation of dark spots due to moisture and oxygen ingress through sealing layers can lead to reduced light emission and reliability issues, as defects in multi-layer sealing structures may not be detected as initial failures, resulting in premature failure during use.

Innovation Solution

A multilayer sealing structure is implemented, with a first sealing layer having a heavy hydrogen diffusion coefficient of 1.0×10−21 m2/sec or more, primarily containing silicon oxynitride, and a second sealing layer with a denser configuration to prevent moisture and oxygen entry, ensuring early detection of defects and reducing dark spot formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cathode protection layer and gas barrier layer both exhibit gas barrier properties, then the sealing layer shows excellent gas barrier properties, but defective portions in both layers result in delayed detection of moisture and oxygen ingress

Engineering Contradiction:

Improvegas barrier propertiesVSAvoiddefect detection timing

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The buffer layer is positioned between the two sealing layers to perform preliminary detection of moisture and oxygen ingress. Before these substances can reach the functional layer and cause dark spots, they must pass through the buffer layer first. This preliminary action creates an early warning system that detects defects in the sealing layers before critical failure occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The buffer layer serves as a cushioning zone that absorbs and detects the ingress of moisture and oxygen before they can cause damage to the functional layer. This beforehand cushioning provides a safety margin that allows detection and potential remediation before actual failure occurs, resolving the detection timing issue.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Difficulty of detecting and measuring

If a single gas barrier layer is used as the sealing layer, then defective portions are detected as initial failures, but the gas barrier properties are not as excellent as with two layers

Engineering Contradiction:

Improvedefect detectionVSAvoidgas barrier properties

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The sealing structure is segmented into three layers with distinct functions: the first sealing layer provides initial protection and some barrier properties, the buffer layer provides detection capability with lower barrier properties, and the second sealing layer provides enhanced barrier properties. This segmentation resolves the contradiction by distributing functions across multiple layers rather than relying on a single layer to perform all functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sealing structure uses a composite of three different material layers with different barrier properties. The first sealing layer and second sealing layer have high barrier properties, while the buffer layer has lower barrier properties intentionally designed for detection. This composite structure combines the advantages of multiple materials to achieve both excellent gas barrier properties and defect detection capability.

Inventive Principle:

Principle #40Composite materials

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 configuration effectively suppresses the reduction in light emission properties and enhances the reliability of organic light emitting devices by detecting defects early, preventing premature failure and ensuring long-term performance.

Implementation Method 1

the first sealing layer has a heavy hydrogen diffusion coefficient of 1.0×10−21 m2/sec or more in the layer at 85° C. in a heavy hydrogen atmosphere

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

a second sealing layer mainly containing silicon oxynitride are successively stacked from a side of the organic light emitting element, and the first sealing layer has a heavy hydrogen diffusion coefficient of 1.0×10−21 m2/sec or more in the layer at 85° C. in a heavy hydrogen atmosphere

Methodology Applied

Scientific EffectPermeation barrier: Permeation

Data Source

PatentUS9843022B2Organic light emitting device and electronic apparatus

Publication Date: 2017.12.12 SEIKO EPSON CORP

AI summary

An organic light emitting device has a substrate, an organic light emitting element disposed on the substrate, and a sealing layer sealing the organic light emitting element by covering the organic light emitting element. The sealing layer is a multilayer body in which a first sealing layer mainly containing an inorganic material, a buffer layer mainly containing a resin material, and a second sealing layer mainly containing silicon oxynitride are successively stacked from a side of the organic light emitting element. The first sealing layer has a heavy hydrogen diffusion coefficient of 1.0×10−21 m2/sec or more at 85° C. in a heavy hydrogen atmosphere.