Organic Electroluminescent Dual-Host Materials for Efficiency and Lifetime

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Solution Overview

Problem

Existing organic electroluminescent devices, particularly those exhibiting triplet emission (phosphorescence), face challenges in efficiency, operating voltage, and lifetime, despite advancements in host and matrix materials.

Innovation Solution

A combination of an electron-transporting host material and a hole-transporting host material, specifically compounds of formulas (1) and (2), is used in the light-emitting layer to enhance device performance, particularly with phosphorescent emitters at concentrations between 2 and 15 wt.%, optimizing efficiency and operating voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent emitters are used in organic electroluminescent devices, then energy efficiency is improved, but device lifetime deteriorates

Engineering Contradiction:

Improveenergy efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

The patent employs a composite host material system consisting of two distinct compounds: a carbazole derivative (Formula 1) providing electron transport and triplet energy, and a deuterated amine compound (Formula 2) providing hole transport. This composite material approach allows the device to achieve both high energy efficiency through phosphorescent emission and extended lifetime through optimized charge transport and reduced non-radiative recombination, resolving the contradiction between efficiency and lifetime

Inventive Principle:

Principle #40Composite materials

2Power

If phosphorescent emitters are used in organic electroluminescent devices, then power efficiency is improved, but operating voltage increases

Engineering Contradiction:

Improvepower efficiencyVSAvoidoperating voltage

Core Design Contradiction:

PowerVSStress or pressure

Solution Approach 1:

The patent optimizes the energy level parameters of the host materials by selecting specific compounds with defined triplet energies (T1) and HOMO/LUMO levels. The carbazole derivative provides triplet energy at 2.7 eV while the deuterated amine provides appropriate hole transport with optimized energy alignment. This parameter optimization enables efficient phosphorescent emission at lower operating voltages by reducing energy losses and improving charge injection barriers

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite host material system resolves the voltage-efficiency contradiction by combining the electron-transporting carbazole derivative with the hole-transporting deuterated amine. This combination creates balanced charge transport pathways that reduce voltage losses while maintaining high power efficiency through phosphorescent emission, achieving both improved power efficiency and reduced operating voltage

Inventive Principle:

Principle #40Composite materials

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 material combination significantly improves the lifetime and efficiency of organic electroluminescent devices, especially in the presence of phosphorescent emitters, while maintaining or reducing operating voltage.

Implementation Method 1

The electron-transporting host material corresponds to a compound of formula (1) from the class of compounds containing a pyridine, pyrimidine, or triazine unit substituted by a dibenzofuran or dibenzothiophene

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Implementation Method 2

the hole-transporting host material corresponds to a deuterated monoamine of formula (2)

Methodology Applied

Scientific EffectHole transport: Conduction (electrical)

Implementation Method 3

In addition to fluorescent emitters, organometallic complexes that exhibit phosphorescence instead of fluorescence are increasingly used as emitting materials

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentEP4410072B1Organic electroluminescent apparatus

Publication Date: 2025.10.29 MERCK PATENT GMBH

AI summary

The present invention relates to an organic electroluminescent apparatus containing a mixture that comprises an electron-transporting host material and a hole-transporting host material, as well as to a formulation containing a mixture of the host materials and to a mixture containing the host materials. The electron-transporting host material corresponds to a compound of formula (1) from the class of compounds containing a pyridine, pyrimidine or triazine unit substituted by a dibenzofuran or dibenzothiophene and the hole-transporting host material corresponds to a deuterated monoamine of formula (2).