Phosphorescent Dopant with Redox-Active Metallocene Ligand

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current organic light-emitting diode (OLED) technologies face challenges in achieving stable and efficient phosphorescent emission, particularly for blue phosphorescent emitters, due to the correlation between optical and electrochemical band gaps, which affects device stability and efficiency.

Innovation Solution

A novel phosphorescent dopant system with a pendant redox-active metallocene ligand is introduced, allowing modulation of the electrochemical gap without altering the optical band gap, thereby enhancing the stability and efficiency of OLEDs by maintaining triplet energy while reducing the electrochemical gap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional phosphorescent emitters are used in OLEDs, then optical emission is achieved, but device stability and efficiency are compromised due to the correlation between optical and electrochemical band gaps

Engineering Contradiction:

Improvedevice stabilityVSAvoidelectrochemical gap

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent separates the optical band gap and electrochemical gap by introducing a pendant redox-active metallocene ligand. This segmentation allows the optical properties (determined by the main conjugated system) to remain independent from the electrochemical properties (modulated by the redox-active ligand), thereby resolving the correlation that limits device stability and efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent modifies the electrochemical parameters of the emitter by incorporating redox-active metallocene ligands with tunable redox potentials. This parameter change enables adjustment of the electrochemical gap without affecting the optical band gap, allowing optimization of device stability and efficiency while maintaining desired optical emission characteristics

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the electrochemical gap is reduced to improve device efficiency, then charge trapping is enhanced, but triplet energy confinement becomes compromised

Engineering Contradiction:

Improvedevice efficiencyVSAvoidtriplet energy confinement

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent segments the functional domains by attaching the redox-active metallocene ligand as a pendant group to the main phosphorescent emitter structure. This spatial segmentation allows the electrochemical gap (affecting charge trapping and efficiency) to be modulated independently from the triplet energy level (affecting energy confinement and stability), resolving the contradiction between device efficiency and triplet energy confinement

Inventive Principle:

Principle #1Segmentation

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 approach results in more stable phosphorescent emitters with improved charge trapping and confinement of triplet energy, leading to higher device efficiency and longer device lifetime.

Implementation Method 1

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

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS10000517B2Organic electroluminescent materials and devices

Publication Date: 2018.06.19 UNIVERSAL DISPLAY CORP

AI summary

Phosphorescent metal complexes comprising a pendant redox-active metallocene are disclosed. These complexes are useful as emitters for phosphorescent OLEDs.