Organic Light Emitting Element Electron Injection Layer Water Resistance

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Solution Overview

Problem

Existing organic light emitting elements face instability due to high reactivity of metal-based electron injection layers with moisture, leading to poor water resistance and short lifespan.

Innovation Solution

Incorporating a 1,1′,3,3a,3′,3′a,4,4′,5,5′,6,6′,7,7a,7′,7′a-hexadecahydro-2,2′-bibenzo[d]imidazolidene compound as an electron injection layer, which has low oxidation potential and is resistant to water, reducing light emission inhibition and enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal-based electron injection layers are used to improve electron injection properties, then electron injection efficiency is improved, but water resistance and stability deteriorate due to high reactivity with moisture

Engineering Contradiction:

Improveelectron injection efficiencyVSAvoidwater resistance

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of the electron injection layer by using organic compounds with specific molecular structures (formula 1) instead of traditional metals. The compound features aromatic substituents (phenyl, naphthyl, fluorenyl groups) that provide both electron injection capability and water resistance, resolving the contradiction between injection efficiency and stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite molecular structures combining electron-donating aromatic groups with imidazolidene core structures. This composite approach creates a material that exhibits both excellent electron injection properties (through the aromatic substituents) and high water resistance (through the stable imidazolidene framework), eliminating the need to choose between injection efficiency and stability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If metal-based electron injection layers are used to improve electron injection properties, then electron injection efficiency is improved, but element lifespan deteriorates due to metal reactivity

Engineering Contradiction:

Improveelectron injection efficiencyVSAvoidelement lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent fundamentally changes the material class from metals to organic compounds with specific structural parameters (formula 1). The organic compound's stable molecular structure prevents degradation reactions that would otherwise limit element lifespan, while maintaining the necessary electron injection efficiency through appropriate substituent selection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive, reactive metal materials with stable organic compounds that have longer operational lifetimes. The organic compound layer acts as a protective interface that prevents direct contact between the cathode and moisture, thereby extending the operational life of the entire light emitting element.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If conventional electron injection layers are used, then manufacturing is simpler, but water resistance and stability are poor

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidwater resistance

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical structure parameters of the electron injection layer material to include water-resistant aromatic substituents on the imidazolidene core. This structural modification maintains compatibility with existing vacuum deposition manufacturing processes while dramatically improving water resistance and long-term stability.

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 use of the 1,1′,3,3a,3′,3′a,4,4′,5,5′,6,6′,7,7a,7′,7′a-hexadecahydro-2,2′-bibenzo[d]imidazolidene compound in the electron injection layer results in a stable and long-life organic light emitting element with improved water resistance and high light emission efficiency.

Implementation Method 1

improvements in electron injection properties are important to migrate toward lower voltages in the element

Methodology Applied

Scientific EffectElectron injection:

Implementation Method 2

excitons are generated by recombination of holes and electrons injected from the above each electrode in a light emitting layer

Methodology Applied

Scientific EffectRecombination of holes and electrons:

Implementation Method 3

when these metals are used for an electron injection layer, a stable organic light emitting element cannot be obtained. This is because the metals used for an electron injection layer have high reactivity to moisture

Methodology Applied

Scientific EffectWater resistance: Hydrophobe

Data Source

PatentUS9846385B2Organic light emitting element and display device

Publication Date: 2017.12.19 CANON KK

AI summary

An organic light emitting element contains an anode and a cathode, and a light emitting layer arranged between the anode and the cathode, and the organic light emitting element further contains an organic compound layer which is arranged between the cathode and the light emitting layer, and touches the cathode. The organic compound layer contains an organic compound represented by the following general formula [1], where R1 to R4 represent substituents.