Crosslinked Ion Complexes for Low Voltage OLEDs

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Solution Overview

Problem

Existing organic electroluminescent elements have insufficient reduction in driving voltage, and the luminous efficiency and driving lifetime are not adequately improved due to the lack of effective ion complex formation and diffusion prevention of electron acceptors.

Innovation Solution

A composition comprising a crosslinking reaction product of a carbazole compound with a crosslinking group and an electron accepting compound with a crosslinking group, used in the hole injection layer and/or hole transport layer, to enhance ion complex formation and charge transport.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electron donors and acceptors are used to form ion complexes, then charge injection is improved, but driving voltage reduction is insufficient

Engineering Contradiction:

Improvecharge injectionVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the molecular structure parameters of both electron donor and acceptor by introducing crosslinking groups. This structural modification enables the formation of stable crosslinked ion complexes that significantly reduce hole injection barriers, achieving driving voltages of 3V or less while maintaining reliable charge injection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system where crosslinked electron donors and crosslinked electron acceptors form a synergistic ion complex. This composite approach combines the advantages of both crosslinked components to achieve superior charge injection and low driving voltage performance that neither component could achieve alone.

Inventive Principle:

Principle #40Composite materials

2Reliability

If electron acceptors are used without crosslinking groups, then ion complex formation occurs, but electron acceptor diffusion to light-emitting layer cannot be prevented

Engineering Contradiction:

Improveion complex formationVSAvoidelectron acceptor diffusion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by introducing crosslinking groups into the electron acceptor molecules before they can diffuse to the light-emitting layer. Upon exposure to UV light or heat, these crosslinking groups form a three-dimensional network structure that immobilizes the electron acceptor, preventing diffusion while maintaining ion complex formation capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes a phase transition approach where the electron acceptor material transitions from a mobile liquid or amorphous state to a crosslinked gel or solid state. This phase change locks the electron acceptor in place, preventing diffusion to the light-emitting layer while preserving its function in ion complex formation.

Inventive Principle:

Principle #36Phase transitions

3Reliability

If crosslinked structures are formed in hole injection/transport layers, then charge transport is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecharge transportVSAvoidcrosslinking process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by incorporating photopolymerizable or thermally polymerizable groups directly into the molecular structures of electron donors and acceptors. The materials themselves provide the crosslinking functionality, eliminating the need for separate crosslinking agents or complex multi-step processes. Crosslinking is achieved through simple UV irradiation or heating of the already-deposited layers.

Inventive Principle:

Principle #25Self-service

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 solution achieves a low driving voltage, high luminous efficiency, and long driving lifetime for organic electroluminescent elements by improving ion complex formation and preventing electron acceptor diffusion.

Implementation Method 1

when an arylamine organic electron donor and an organic electron acceptor are mixed at an appropriate ratio to allow N atoms included in the arylamine to partially form an ion complex with the organic electron acceptor

Methodology Applied

Scientific EffectIon complex formation:

Implementation Method 2

an organic electroluminescent element having a low driving voltage, high luminous efficiency, and a long driving lifetime by using a hole injection layer and/or a hole transport layer containing a crosslinking reaction product

Methodology Applied

Scientific EffectCrosslinking:

Data Source

PatentUS20250127046A1Composition, organic electroluminescent element and method for producing same, display device, and lighting device

Publication Date: 2025.04.17 MITSUBISHI CHEM CORP

AI summary

A composition comprising: a carbazole compound having a crosslinking group and represented by formula (71) or (72) below; and an electron accepting compound having a crosslinking group and represented by formula (81) below.