2,2'-Bibenzimidazolidene Electron Injection Layer

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Solution Overview

Problem

Organic light-emitting elements with electron injection layers containing metal atoms are prone to oxidation and water reactivity, leading to reduced stability and lifetime.

Innovation Solution

A 2,2′-bibenzo[d]imidazolidene compound with heteromonocyclic groups at the 1-, 1′-, 3-, and 3′-positions is developed, which is stable to oxidation and moisture, enhancing electron injectability and stability by reducing reactivity with oxygen and water.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a compound containing a metal atom is used in the electron injection layer, then electron injectability is improved, but stability against oxidation and water reactivity deteriorates

Engineering Contradiction:

Improveelectron injectabilityVSAvoidstability against oxidation and water

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention extracts and eliminates metal atoms from the electron injection layer compound, replacing them with organic groups. Specifically, the compound of formula (1) uses organic substituents (Ar1-Ar4) instead of metal atoms, thereby removing the source of oxidation and water reactivity while maintaining electron injection functionality through the organic molecular structure

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the chemical composition parameters of the electron injection layer by transitioning from metal-containing compounds to purely organic compounds with specific heteromonocyclic groups. This parameter change (from metal to organic) fundamentally alters the chemical stability profile while preserving the electronic properties needed for electron injection

Inventive Principle:

Principle #35Parameter changes

2Reliability

If compounds unstable to oxidation in air are used, then electron injectability can be achieved, but ease of operation deteriorates due to difficulty in handling in air

Engineering Contradiction:

Improveelectron injectabilityVSAvoidease of handling in air

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention converts the typically harmful effect of air exposure (oxidation) into a beneficial situation by designing a compound that is inherently resistant to oxidation. The heteromonocyclic groups and organic structure create steric and electronic protection against oxidative degradation, allowing the compound to be handled in air without special precautions while maintaining high electron injectability

Inventive Principle:

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

Data Source

PatentUS10193084B22,2′-bibenzo[D]imidazolidene compound having heteromonocyclic groups at the 1-, 1′-, 3- and 3′- positions, and organic light-emitting element and display device containing the same

Publication Date: 2019.01.29 CANON KK

AI summary

A 2,2′-bibenzo[d]imidazolidene compound expressed by the following general formula (1). In general formula (1), Ar1 to Ar4 each represent a substituted or unsubstituted heteromonocyclic group. R1 to R8 each represent a hydrogen atom or a substituent.