Carbazole Host Compound Structure for Stable High-Temperature OLED Emission

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Solution Overview

Problem

Existing organic electroluminescent elements using phosphorescence emission suffer from inefficiencies in emission efficiency, lifetime, and thermal stability, particularly in high-temperature conditions.

Innovation Solution

Incorporation of an aromatic heterocyclic derivative with a specific structure, featuring a carbazole ring and a condensed ring structure, into the organic layer to stabilize the molecule and enhance charge injection properties, thereby improving emission efficiency and lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional host compounds with multi-condensed ring structures are used in phosphorescence emitting layers, then emission efficiency is improved to some extent, but thermal stability deteriorates under high-temperature conditions

Engineering Contradiction:

Improveemission efficiencyVSAvoidthermal stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention changes the molecular structure parameters of the host compound by introducing a carbazole ring with specific substituents (Formula 1 structure), which modifies the physical and chemical properties to achieve both high emission efficiency and thermal stability simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite molecular structure combining carbazole ring, condensed ring system, and specific substituents to form a new host compound that integrates the advantages of different structural motifs for enhanced performance

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If phosphorescence emission mode is used in organic EL elements, then emission efficiency can be 4 times larger than fluorescence emission, but control of emission center position and recombination stability becomes difficult

Engineering Contradiction:

Improveemission efficiencyVSAvoidemission stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The invention introduces electron-donating substituents at specific positions (2-position and/or 6-position) of the carbazole ring to create local electronic property variations that control charge distribution and stabilize the emission center position in the phosphorescence emitting layer

Inventive Principle:

Principle #3Local quality

3Use of energy by moving object

If existing host compounds are used to improve emission efficiency, then some performance enhancement is achieved, but lifetime and emission stability remain insufficient

Engineering Contradiction:

Improveemission efficiencyVSAvoidemission lifetime

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of moving object

Solution Approach 1:

The invention optimizes molecular parameters including introducing electron-donating substituents and designing specific ring structures to enhance charge injection and transport properties, which improves both emission efficiency and device lifetime simultaneously

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 aromatic heterocyclic derivative enhances emission efficiency, extends the element's lifetime, and improves thermal stability under high-temperature conditions, ensuring stable operation and high productivity.

Implementation Method 1

Incorporation of an aromatic heterocyclic derivative with a specific structure, featuring a carbazole ring and a condensed ring structure, into the organic layer to stabilize the molecule

Methodology Applied

Scientific EffectMolecular stabilization:

Implementation Method 2

an organic EL element utilizing phosphorescence emission from the excited triplet will realize an emission efficiency of 4 times larger compared with an emission efficiency of an organic EL element utilizing fluorescence emission

Methodology Applied

Scientific EffectPhosphorescence emission: Phosphorescence

Implementation Method 3

An organic electroluminescent element is a luminescent element which uses light emission (fluorescence or phosphorescence) from this exciton

Methodology Applied

Scientific EffectFluorescence emission: Fluorescence

Data Source

PatentUS12559459B2Aromatic heterocyclic derivative, and organic electroluminescent element, illumination device, and display device using aromatic heterocyclic derivative

Publication Date: 2026.02.24 MERCK PATENT GMBH

AI summary

The present invention addresses the problem of providing a novel aromatic heterocyclic derivative, providing an organic EL element that uses the derivative and has high luminous efficiency, long luminescence life, and few changes over time when used under high temperatures, and providing a display device and an illumination device that are equipped with the organic El element. This aromatic heterocyclic derivative is characterized by having a specific structure which includes a carbazole ring.