1,2,3-Triazole Metal Complexes for OLED Efficiency and Solubility

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Solution Overview

Problem

Organic electroluminescent devices (OLEDs) face challenges with efficiency, operating voltage, and lifetime, particularly for short-wave emitters like green and blue, and many phosphorescent emitters have inadequate solubility for solution processing, making it difficult to improve their performance.

Innovation Solution

The development of specific metal chelate complexes, such as those described by Formula (1), which include a metal (iridium, rhodium, platinum, or palladium) bonded to bidentate ligands via nitrogen and carbon, offering improved solubility and efficiency, and are used in organic electroluminescent devices to enhance performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent emitters are used to improve energy efficiency, then energy efficiency increases, but solubility deteriorates

Engineering Contradiction:

Improveenergy efficiencyVSAvoidsolubility

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent modifies the chemical structure of phosphorescent emitters by introducing specific ligand substitutions and molecular weight adjustments. This changes the physical-chemical parameters of the compounds to achieve a balance between maintaining phosphorescent efficiency and improving solubility for solution processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material strategies by combining phosphorescent metal complexes with specific host materials and ligands. The use of cyclometalated ligands with tailored substituents creates composite molecular structures that simultaneously provide phosphorescent functionality and improved solubility characteristics.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If phosphorescent emitters are used to improve energy efficiency, then energy efficiency increases, 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 optimizes molecular parameters of phosphorescent emitters including steric bulk of substituents, ligand field strength, and metal-ligand bond stability. These parameter changes enhance the chemical stability and photostability of the emitters, thereby extending device lifetime while preserving phosphorescent efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent develops readily synthesizable phosphorescent emitter structures that can be processed from solution, enabling more efficient manufacturing and potential replacement strategies that improve overall device economics and longevity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Power

If conventional phosphorescent emitters are used, then phosphorescence is achieved, but operating voltage increases

Engineering Contradiction:

Improvephosphorescence emissionVSAvoidoperating voltage

Core Design Contradiction:

PowerVSStress or pressure

Solution Approach 1:

The patent modifies the HOMO-LUMO energy gap and charge injection characteristics by selecting appropriate metal centers (Ir, Pt, Rh, Pd) and ligand combinations. These parameter changes optimize the electrical properties and energy levels of the phosphorescent emitters, leading to reduced operating voltages while maintaining efficient phosphorescence emission.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If solution processing is enabled by improving solubility, then ease of manufacture increases, but device performance may deteriorate

Engineering Contradiction:

ImprovesolubilityVSAvoiddevice performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces localized functional groups and substituents on the ligand frameworks that specifically enhance solubility without interfering with the core phosphorescent activity. This local modification strategy allows solution processing while preserving the essential photophysical properties and device performance.

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

These metal complexes result in improved solubility, efficiency, and extended lifetime of OLEDs, reducing operating voltages and enabling better film formation, making them suitable for mass production and various applications, including display and illumination technologies.

Implementation Method 1

The emitting materials being employed here are increasingly organometallic complexes which exhibit phosphorescence instead of fluorescence

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentEP2797940B1Metal complexes comprising 1,2,3-triazoles

Publication Date: 2016.02.24 MERCK PATENT GMBH

AI summary

The present invention relates inter alia to a new class of metal complexes comprising 1,2,3-triazoles having improved solubility and enhanced electro-optical properties. The present invention further relates to the preparation and use of these compounds.