Organic Electroluminescence Device Hole Transport Materials

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Solution Overview

Problem

Organic electroluminescence devices face issues with charge transfer between molecules of different structures, leading to increased voltage requirements and reduced luminous efficiency.

Innovation Solution

Incorporating an aromatic amine derivative with a thiophene group as a hole injecting material and another with a carbazole skeleton and diarylamino group as a hole transporting material, using specific substituents to reduce steric hindrance and enhance charge transport characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If aromatic amine derivatives with specific substituents are used as hole injecting and transporting materials, then charge transfer between molecules progresses smoothly, but device complexity increases due to specific structural requirements

Engineering Contradiction:

Improveluminous efficiencyVSAvoidmolecular structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the molecular structure parameters of hole transporting materials. Specifically, it uses aromatic amine derivatives with carbazole skeletons and diarylamino groups bonded through linking groups (formula 1), where the structural parameters (linking groups L1-L6, substituents R1-R6) are optimized to achieve smooth charge transfer. This structural parameter optimization enables efficient charge transport while maintaining practical device complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining aromatic amine derivatives with thiophene groups (formula 2) as hole injecting materials and aromatic amine derivatives with carbazole skeletons (formula 1) as hole transporting materials. This composite approach leverages the complementary properties of different molecular structures to achieve smooth charge transfer between molecules with different structures, resolving the contradiction between efficiency and complexity

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If charge transfer between molecules of different structures is improved, then luminous efficiency increases, but driving voltage may increase due to material selection constraints

Engineering Contradiction:

Improveluminous efficiencyVSAvoiddriving voltage

Core Design Contradiction:

Loss of energyVSStress or pressure

Solution Approach 1:

The patent uses intermediary materials with specific molecular structures as mediators to facilitate charge transfer. The aromatic amine derivative with carbazole skeleton (formula 1) acts as an intermediary hole transporting material that bridges the charge transfer between different molecular structures. The carbazole skeleton and diarylamino group configuration enable efficient charge transport while maintaining low driving voltage, resolving the contradiction between luminous efficiency and driving voltage

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If aromatic amine derivatives with carbazole skeletons and diarylamino groups are used, then hole transport efficiency improves, but manufacturing complexity increases due to synthesis requirements

Engineering Contradiction:

Improvehole transport efficiencyVSAvoidsynthesis ease

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent optimizes manufacturing parameters by defining specific structural parameters (linking groups L1-L6, substituents R1-R6) that can be varied within controlled ranges. This parameter optimization enables efficient hole transport while maintaining reasonable synthesis feasibility through systematic structural design rather than complex custom synthesis

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 solution enables organic electroluminescence devices to operate at lower voltages with improved luminous efficiency, making them suitable for full-color display applications and reducing production costs.

Implementation Method 1

charge transfer between molecules having different molecular structures in such material as described above does not progress smoothly

Methodology Applied

Scientific EffectCharge transfer: Conduction (electrical)

Implementation Method 2

an aromatic amine derivative having a carbazole skeleton to which a diarylamino group is bonded through a linking group as a hole transporting material

Methodology Applied

Scientific EffectCharge transport: Conduction (electrical)

Implementation Method 3

the electron recombines with the hole in the light emitting layer to produce an excited state, and energy generated upon return of the electron from the excited state to its ground state is discharged as light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8367222B2Organic electroluminescent device

Publication Date: 2013.02.05 IDEMITSU KOSAN CO LTD

AI summary

Provided is an organic electroluminescence device, including: an anode; a cathode; and organic thin film layers provided between the anode and the cathode, in which: the organic thin film layers have a light emitting layer, and have a hole injecting layer and a hole transporting layer, or a hole injecting/transporting layer on a side which is closer to the anode than the light emitting layer is; the hole injecting layer or the hole injecting/transporting layer contains an aromatic amine derivative having a specific substituent, and the hole transporting layer or the hole injecting/transporting layer contains an aromatic amine derivative having a specific substituent.