Hexadentate Ligand OLED Emitter Stability

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Solution Overview

Problem

There is a need for novel thermally- and photochemically-stable hexadentate phosphorescent complexes in organic light emitting diodes (OLEDs) to enhance their stability and performance.

Innovation Solution

A compound with a specific hexadentate ligand structure, coordinated to a metal, is used in the organic layer of OLEDs, providing increased thermal and photochemical stability through a unique ligand tethering architecture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional phosphorescent emissive molecules are used in OLEDs, then the devices can achieve light emission with tunable wavelengths, but the thermal and photochemical stability of the devices is insufficient

Engineering Contradiction:

Improvethermal and photochemical stabilityVSAvoidligand structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The hexadentate ligand is divided into three separate bidentate moieties (first, second, and third bidentate ligands) that coordinate to the metal center independently. This segmentation allows each bidentate ligand to be optimized for specific functions while collectively providing enhanced stability through multiple coordination sites, resolving the contradiction between stability and structural simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The hexadentate ligand structure serves multiple functions simultaneously: it provides thermal stability through strong metal coordination, photochemical stability through extended conjugation, and tunable emission wavelengths through adjustable substituents. This multi-functionality allows a single ligand architecture to address multiple performance requirements without proportionally increasing complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If the ligand structure is simplified for easier manufacture, then the manufacturing cost decreases, but the thermal and photochemical stability of the phosphorescent complex is reduced

Engineering Contradiction:

Improveligand synthesis easeVSAvoidthermal and photochemical stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Three bidentate ligands are merged into a single hexadentate ligand structure that coordinates to the metal center through multiple sites. This merging creates a chelate effect that significantly enhances thermal and photochemical stability compared to separate bidentate ligands, while the modular design of the bidentate units maintains reasonable synthetic accessibility through established coordination chemistry protocols

Inventive Principle:

Principle #5Merging (Combining)

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 this compound in OLEDs results in improved thermal and photochemical stability, leading to enhanced performance and longevity of the devices.

Implementation Method 1

One application for phosphorescent emissive molecules is a full color display

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10941170B2Organic electroluminescent materials and devices

Publication Date: 2021.03.09 UNIVERSAL DISPLAY CORP

AI summary

The present invention includes novel hexadentate metal complexes. The complexes hexadentate ligands of the present invention may be useful as improved emitters in an OLED device.