Light-Emitting Device Capping Layer Metal Ion Diffusion Barrier

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Solution Overview

Problem

Existing light-emitting devices with metal fluoride capping layers suffer from diffusion issues with metal salt molecules, poor uniformity, and airtightness, leading to degradation in optical properties and reliability due to water and oxygen ingress.

Innovation Solution

A light-emitting device structure incorporating a lower electrode, a functional layer with a light-emitting layer, an upper electrode, a first capping layer made of organic insulating material, and a second capping layer containing a metal complex, with ligand layers adjacent to the second capping layer to form stable metal complexes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal fluoride capping layer is used, then optical properties are adjusted and protected, but metal salt molecules diffuse into adjacent layers causing degradation

Engineering Contradiction:

Improvedevice reliabilityVSAvoidmetal salt diffusion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces an organic insulating material layer as an intermediary between the metal fluoride capping layer and the adjacent functional layers. This intermediate layer acts as a diffusion barrier, preventing metal salt molecules from migrating into neighboring layers while maintaining the optical and protective functions of the metal fluoride layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite capping structure combining metal fluoride material with organic insulating material. This composite approach leverages the high refractive index and protective properties of metal fluoride while using the organic insulating material to suppress metal salt diffusion, achieving both optical performance and compositional stability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If water enters the capping layer containing metal salt, then metal ions are generated, but this causes entry into adjacent layers and deterioration

Engineering Contradiction:

Improvedevice reliabilityVSAvoidwater and oxygen ingress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The organic insulating material layer serves as a protective intermediary that blocks water and oxygen from reaching the metal fluoride capping layer. By preventing moisture ingress at the interface, this intermediate layer stops the generation of metal ions and their subsequent migration into adjacent layers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potential harm of metal salt hygroscopy into a benefit by using the organic insulating material to control and localize any water interaction. The intermediate layer ensures that even if water reaches the metal fluoride, the resulting metal ions are contained and prevented from migrating, turning a harmful property into a controlled phenomenon.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Illumination intensity

If metal salt capping layer is used, then optical properties are adjusted, but uniformity and airtightness deteriorate

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidlayer uniformity

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent creates a composite capping structure where the organic insulating material layer is combined with the metal fluoride layer. The organic insulating material provides excellent film formation and uniformity, while the metal fluoride contributes high refractive index for improved light extraction efficiency, achieving both manufacturing precision and optical performance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different materials with different properties to different locations in the capping structure. The organic insulating material is positioned where uniformity and barrier properties are critical, while the metal fluoride is positioned where optical properties are most important, optimizing both uniformity and light extraction efficiency in their respective zones.

Inventive Principle:

Principle #3Local quality

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 enhances optical properties and reliability by preventing metal ion diffusion, improving uniformity and airtightness, and reducing degradation from water and oxygen, resulting in improved light extraction efficiency and extended device lifetime.

Implementation Method 1

containing ligands that form a complex together with either a metal element, or metal ions, contained in the metal salt

Methodology Applied

Scientific EffectComplex formation: Chemical Bonding

Data Source

PatentUS20250048915A1Light-emitting device

Publication Date: 2025.02.06 SHARP DISPLAY TECHNOLOGY CORP

AI summary

A light-emitting device includes: a lower electrode; a functional layer including at least a light-emitting layer; an upper electrode; a first capping layer containing an organic insulating material; and a second capping layer containing a metal complex, all of which are stacked on top of another in a stated order.