Macrocyclic Ligand OLEDs for Stability and Efficiency

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Solution Overview

Problem

Current organic light emitting devices (OLEDs) face challenges in achieving long lifetimes, high stability, and efficiency, particularly in full-color displays, where prior art compounds fall short in meeting industry standards for stability and performance.

Innovation Solution

The development of OLEDs incorporating macrocyclic electrophosphors with multidentate ligand systems, specifically organometallic compounds featuring a heavy metal atom and a macrocyclic ligand, which enhance the stability and efficiency of the phosphorescent emissive materials by confining the organic molecule in close proximity to a high atomic number atom, utilizing a tetradentate or hexadentate ligand system to increase the stability of metal complexes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional phosphorescent emissive materials are used in OLEDs, then the device can emit light with acceptable initial efficiency, but the lifetime and stability are insufficient to meet industry standards for full-color displays

Engineering Contradiction:

ImproveOLED lifetime and stabilityVSAvoiddevice lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the molecular structure parameters of the phosphorescent emitter by incorporating a heavy metal atom (such as iridium) into the molecular core. This structural parameter change increases the atomic number and enhances spin-orbit coupling, which improves phosphorescent efficiency and device stability, thereby extending operational lifetime while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material design by creating organometallic complexes that combine organic ligands with a heavy metal center. This composite structure integrates the beneficial properties of both organic materials (processability, flexibility) and heavy metals (high quantum yield, stability), resulting in phosphorescent emitters that simultaneously achieve long lifetime and high reliability

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If prior art compounds are used to achieve full-color display, then the device can display multiple colors, but the stability and performance fall short of industry standards

Engineering Contradiction:

Improvefull-color display capabilityVSAvoidstability and performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by designing different ligand environments around the heavy metal center to tune the emission color while maintaining stability. Each ligand system is optimized locally to provide specific photophysical properties (emission wavelength, quantum yield) while the heavy metal core provides universal stability, enabling full-color display with high reliability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by systematically varying ligand substituents and heavy metal selection to optimize both color emission properties and stability parameters. This dual optimization allows the material to meet full-color display requirements while achieving industry-standard stability and performance

Inventive Principle:

Principle #35Parameter changes

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 approach results in improved stability and efficiency of OLEDs, enabling longer lifetimes and higher performance, particularly in full-color displays, by leveraging the heavy atom effect and multidentate ligand systems to stabilize the metal complexes and enhance phosphorescent emission.

Implementation Method 1

confining the organic molecule in close proximity to a high atomic number atom, utilizing a tetradentate or hexadentate ligand system to increase the stability of metal complexes

Methodology Applied

Scientific EffectHeavy atom effect:

Implementation Method 2

phosphorescent emitting materials with improved stability and efficiency when incorporated into an OLED

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS7655322B2OLEDs utilizing macrocyclic ligand systems

Publication Date: 2010.02.02 SOUTHERN CALIFORNIA UNIV OF THE

AI summary

The present invention relates to efficient organic light emitting devices (OLEDs), and more specifically to organic materials used in such devices. More specifically, the present invention relates to materials with improved stability and efficiency when incorporated into an OLED.