Mixed Host Materials for Phosphorescent OLED Lifetime and Voltage

Solution Overview

Problem

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

Innovation Solution

A combination of a compound of formula (1) as the first host material and a compound of formula (2a) as the second host material in the light-emitting layer, optimized with specific structural and energetic considerations, enhances device performance.

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 and power efficiency are improved, but device lifetime is reduced

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 a bipolar host material combined with either an electron-transporting host material or a hole-transporting host material. This composite approach creates a synergistic effect where the bipolar host provides balanced charge transport while the auxiliary host material enhances either electron or hole transport specifically, thereby improving overall device efficiency and lifetime without sacrificing the benefits of phosphorescent emission.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

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

Engineering Contradiction:

Improveenergy efficiencyVSAvoidoperating voltage

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent employs a composite host material system consisting of a bipolar host material combined with either an electron-transporting host material or a hole-transporting host material. This composite approach creates a synergistic effect where the bipolar host provides balanced charge transport while the auxiliary host material enhances either electron or hole transport specifically, thereby improving overall device efficiency and lifetime without sacrificing the benefits of phosphorescent emission.

Inventive Principle:

Principle #40Composite materials

3Device complexity

If single host material is used in the light-emitting layer, then device complexity is reduced, but device performance and lifetime are limited

Engineering Contradiction:

Improvematerial composition complexityVSAvoiddevice lifetime

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The patent employs a composite host material system consisting of a bipolar host material combined with either an electron-transporting host material or a hole-transporting host material. This composite approach creates a synergistic effect where the bipolar host provides balanced charge transport while the auxiliary host material enhances either electron or hole transport specifically, thereby improving overall device efficiency and lifetime without sacrificing the benefits of phosphorescent emission.

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

This combination significantly improves the lifetime and efficiency of organic electroluminescent devices, particularly in phosphorescent OLEDs, while maintaining or reducing operating voltage.

Implementation Method 1

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

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

The present invention relates to an organic electroluminescent device comprising an electron-transporting host material and a hole-transporting host material

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP4031638B1Mixture of two host materials, and organic electroluminescent device comprising same

Publication Date: 2026.01.14 MERCK PATENT GMBH

AI summary

The invention relates to an organic electroluminescent device containing a mixture which comprises an electron-transporting host material and a hole-transporting host material, 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 the formula (1) of the class of compounds containing two triazine units. The hole-transporting host material corresponds to a compound of the formula (2) of the class of biscarbazoles or derivatives thereof.