Iridium Complex Ligands for Saturated OLED Color Emission

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Solution Overview

Problem

Current organic light-emitting diode (OLED) technologies face challenges in achieving saturated color emission, particularly in red, green, and blue pixels, which is crucial for full-color displays, as existing materials do not efficiently align in emissive film layers to produce desired color coordinates.

Innovation Solution

A compound of Formula Ir(LA)x(LB)y(LC)z is introduced, where x, y, and z vary within specific ranges, with ligands LA, LB, and LC being bidentate and having specific structural characteristics, including monocyclic or polycyclic rings and heterocyclic structures, to improve emission color and spectrum alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional organic materials are used in OLEDs, then device fabrication is simpler and cost is lower, but color emission saturation and accuracy deteriorate

Engineering Contradiction:

Improvecolor emission saturationVSAvoidmaterial structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent modifies the molecular parameters of organic compounds by incorporating specific heterocyclic rings (pyridine, pyrimidine, triazine) and adjusting ligand structures to achieve precise color emission coordinates. This allows tuning of emission properties without fundamentally changing the device architecture, resolving the contradiction between color accuracy and device complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite organic compounds combining multiple heterocyclic moieties within single molecules. These composite structures enable simultaneous control of emission color, stability, and efficiency, achieving saturated color emission while maintaining reasonable device fabrication processes.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If white OLED with absorption filters is used, then saturated colors can be achieved, but device efficiency and brightness deteriorate due to light absorption losses

Engineering Contradiction:

Improvecolor saturationVSAvoidlight emission efficiency

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent extracts and eliminates the need for absorption filters by directly engineering organic compounds to emit saturated colors. This removes the energy-lossy filtering step while achieving the desired color saturation, directly resolving the contradiction between color accuracy and energy efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the passive optical filtering mechanism with active molecular emission control. By designing compounds with specific heterocyclic structures that inherently emit saturated colors, the system substitutes filter-based color generation with molecule-based color emission, improving energy efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If organic materials are used for flexibility, then device flexibility is improved, but color emission accuracy and stability deteriorate

Engineering Contradiction:

Improvedevice flexibilityVSAvoidcolor emission accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces specific heterocyclic ring structures (pyridine, pyrimidine, triazine) at localized positions within the organic molecules to enhance emission stability and accuracy. These localized structural modifications provide color precision while maintaining the overall flexibility of the organic material system.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of accepting that flexibility compromises color accuracy, the invention inverts the approach by designing rigid heterocyclic cores within flexible organic frameworks. This allows the material to maintain both flexibility at the macro scale and color emission precision at the molecular level.

Inventive Principle:

Principle #13The other way round (Inversion)

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 compound enhances the alignment and emission properties in OLEDs, leading to improved device performance and color accuracy, specifically in achieving saturated red, green, and blue emissions.

Implementation Method 1

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

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

One application for phosphorescent emissive molecules is a full color display

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS20250011355A1Organic electroluminescent materials and devices

Publication Date: 2025.01.09 UNIVERSAL DISPLAY CORP

AI summary

A compound of Formula Ir(LA)x(LB)y(LC)z is provided. In Formula Ir(LA)x(LB)y(LC)z, x, Y, and z are non-negative integers; x+y+z=3; LA has a structure of Formula I,LB and LC are bidentate ligands; moiety A is a monocyclic ring or a polycyclic fused ring system; ring C is a 5- or 6-membered heterocyclic ring; each of Z, Z1, X1 to X6 is independently C or N; each of X and Y is a linker that is one-atom in length; each independently represents a single bond or a double bond; each R, R′, RA, RB, and RC is hydrogen or a General Substituent defined herein. Formulations, OLEDs, and consumer products containing the compound are also provided.