OLED Host Material Pairing for Efficiency and Lifetime

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Solution Overview

Problem

Conventional organic electroluminescent devices face challenges in achieving long lifetime and high efficiency, particularly in medium- and large-sized OLED panels, where the luminance of OLEDs is often compromised by short device lifetime.

Innovation Solution

A combination of specific host materials, represented by compounds in formulas 1 and 2, are used in the organic electroluminescent device, comprising a first host material with a nitrogen-containing heteroaryl and a second host material with varied substituents, to enhance thermal stability, electrochemical stability, and adhesion, thereby improving the device's power efficiency and longevity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent materials are used to achieve high luminous efficiency, then power efficiency is improved, but device lifetime deteriorates

Engineering Contradiction:

Improvepower 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 comprising two distinct host compounds (Formula 1 and Formula 2) with complementary properties. The first host material (Formula 1) provides high glass transition temperature and thermal stability, while the second host material (Formula 2) contributes to electrochemical stability and morphology control. This composite approach allows the device to achieve both high power efficiency through phosphorescent dopant and extended lifetime through the synergistic host materials, resolving the contradiction between efficiency and durability.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If luminance of OLED is increased to improve display quality, then illumination intensity is improved, but device lifetime deteriorates

Engineering Contradiction:

ImproveluminanceVSAvoiddevice lifetime

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent modifies key material parameters including glass transition temperature, pyrolysis temperature, and electrochemical stability through the design of specific host molecule structures. By optimizing these parameters in the host materials, the device can maintain high luminance levels while improving thermal and electrochemical stability, thereby extending device lifetime without sacrificing display quality.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If host material purity is increased to achieve high efficiency, then power efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvepower efficiencyVSAvoidmanufacturing complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent introduces specific local structural features in the host materials, such as nitrogen-containing heteroaryl groups in Formula 1 and specific substituent patterns in Formula 2. These localized structural modifications provide high glass transition temperature and electrochemical stability without requiring extreme purity levels, thereby maintaining power efficiency while simplifying manufacturing processes.

Inventive Principle:

Principle #3Local quality

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 use of these host materials results in organic electroluminescent devices with improved power efficiency and extended lifetime, as demonstrated by increased luminance maintenance and prolonged operational hours compared to conventional devices.

Implementation Method 1

An organic electroluminescent device (OLED) changes electric energy into light by applying electricity to an organic electroluminescent material

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

as an energy transmitter, a host material should preferably have high purity and a suitable molecular weight

Methodology Applied

Scientific EffectEnergy transfer:

Implementation Method 3

a host material is required to have high glass transition temperature and pyrolysis temperature to achieve thermal stability

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 4

in order to be deposited under vacuum

Methodology Applied

Scientific EffectVacuum deposition: Physical Vapour Deposition

Data Source

PatentUS20230345827A1Plurality of host materials and organic electroluminescent device comprising the same

Publication Date: 2023.10.26 DUPONT SPECIALTY MATERIALS KOREA LTD

AI summary

The present disclosure relates to a plurality of host materials comprising a first host material having a compound represented by formula 1, and a second host material having a compound represented by formula 2, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds of the present disclosure as host materials, it is possible to provide an organic electroluminescent device having long lifetime properties while having an equivalent or improved level of power efficiency compared to conventional organic electroluminescent devices.