Bipolar Host Triphenylene Composition for OLED Lifetime

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Solution Overview

Problem

There is a need for improved materials to enhance the performance of organic electroluminescent devices, particularly in terms of lifetime, efficiency, and operating voltage, especially when used with green-phosphorescing emitters, as existing bipolar host and uncharged co-host combinations fall short in these aspects.

Innovation Solution

A composition comprising bipolar compounds of specific formulas and triphenylene derivatives is used, which are incorporated into the emission layer at concentrations between 2% and 15% by weight, optimizing device properties such as lifetime and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing bipolar host and uncharged co-host combinations are used in green-phosphorescing OLEDs, then device fabrication is straightforward, but device lifetime and efficiency are insufficient

Engineering Contradiction:

Improvedevice lifetimeVSAvoidhost material combination complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical structure parameters of the host materials by introducing specific substituents (carbazole, dibenzofuran, dibenzothiophene units with electron-deficient heteroaromatics) to optimize HOMO/LUMO energy levels and triplet energy, thereby improving device lifetime and efficiency without changing the fundamental material combination approach

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite host material systems by combining bipolar compounds (formula 1) with uncharged co-hosts (formula 2) in specific weight ratios (30-70 wt% bipolar host), where the synergistic interaction between the two components enhances device performance beyond what single materials can achieve

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If conventional host materials are used in phosphorescent emitters, then material selection is simple, but energy efficiency and power efficiency are limited

Engineering Contradiction:

Improveenergy efficiencyVSAvoidhost material structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent optimizes energy efficiency by carefully selecting and adjusting the triplet energy (T1) and HOMO/LUMO energy levels of the host materials to match the phosphorescent emitter characteristics, maximizing energy transfer efficiency and reducing energy loss while managing the increased structural complexity through systematic molecular design

Inventive Principle:

Principle #35Parameter changes

3Reliability

If standard bipolar hosts are used in OLEDs, then device operation is simple, but operating voltage and lifetime require improvement

Engineering Contradiction:

Improvedevice lifetimeVSAvoiddevice operation simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent improves device lifetime by optimizing the HOMO/LUMO energy level alignment and triplet energy of the bipolar host materials to enhance charge transport balance and reduce degradation mechanisms, while maintaining operational simplicity through straightforward device architecture and standard fabrication processes

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11450809B2Composition for organic electronic devices

Publication Date: 2022.09.20 MERCK PATENT GMBH

AI summary

The present invention relates to a composition comprising a specific bipolar host and a triphenylene derivative, to the use thereof in electronic devices and electronic devices comprising said composition.