Organometallic Complexes for Red OLED Efficiency

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Solution Overview

Problem

Current organic light-emitting diode (OLED) technologies face challenges in achieving high external quantum efficiency and color stability for red phosphorescent materials, particularly in full color displays requiring saturated red, green, and blue pixels.

Innovation Solution

The development of organometallic complexes with specific quinazoline-based ligands and branched acetylacetone derivatives, which are used in OLEDs to form red phosphorescent materials with improved external quantum efficiency, color, and lifetime, are incorporated into the organic light-emitting devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional phosphorescent materials are used in OLEDs, then device structure is simple, but external quantum efficiency and color stability are insufficient

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoidmaterial structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs composite organometallic materials combining iridium or platinum centers with specific organic ligands (C^N and N^N types) to achieve high external quantum efficiency and color stability. The composite structure integrates the photophysical properties of metal centers with the tunable electronic structures of organic ligands, resolving the contradiction between performance improvement and material complexity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent systematically varies ligand parameters (substituent positions, types, and combinations) to optimize the photophysical properties of phosphorescent emitters. By changing ligand parameters such as introducing electron-donating or electron-withdrawing groups at specific positions, the patent achieves precise control over emission color and efficiency, thereby improving external quantum efficiency while managing material complexity.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If red phosphorescent materials are optimized for saturated color, then color quality improves, but external quantum efficiency decreases

Engineering Contradiction:

Improvecolor stabilityVSAvoidexternal quantum efficiency

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent introduces different substituent groups at specific local positions of the ligand structure to independently control color properties and efficiency. For example, electron-donating groups are placed at positions that enhance radiative decay rates for efficiency, while electron-withdrawing groups are positioned to red-shift emission for saturated red color. This local differentiation resolves the contradiction between color stability and external quantum efficiency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent systematically adjusts ligand parameters including substituent types, positions, and metal center selection to simultaneously optimize emission wavelength and quantum efficiency. By changing the combination of C^N and N^N ligands and their substitution patterns, the patent achieves saturated red emission with high external quantum efficiency, resolving the traditional trade-off between color quality and efficiency.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional OLED materials are used, then manufacturing cost is low, but luminous efficiency and lifetime are limited

Engineering Contradiction:

Improveluminous efficiencyVSAvoidmaterial synthesis complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent divides the phosphorescent emitter into modular components: metal center (Ir or Pt), C^N ligand, and N^N ligand, each with specific functional groups. This segmentation allows independent optimization of each component's synthesis and assembly, facilitating manufacturing while achieving high luminous efficiency and extended device lifetime through precise molecular design.

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

These complexes enhance the external quantum efficiency and color stability of red phosphorescent OLEDs, resulting in devices with higher luminous efficiency and external quantum efficiency compared to traditional materials.

Implementation Method 1

red phosphorescent materials with improved external quantum efficiency, color, and lifetime

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

PatentUS11024816B2Organic electroluminescent materials and devices

Publication Date: 2021.06.01 UNIVERSAL DISPLAY CORP

AI summary

Compounds having a structure of Formula I, Formula II, or Formula III, devices containing the same, and formulations containing the same are described.In Formulas (I), (II), and (III), X2 to X8 are C or N; at least one of X2 to X8 is N; R1, R2, R3, and R4 are independently alkyl or cycloalkyl; at least one of R1 to R4 has at least two C atoms; R5 is hydrogen, deuterium, alkyl, cycloalkyl, or a combination thereof; R6, R7, and R8 are independently hydrogen, deuterium, alkyl, cycloalkyl, and combinations thereof; and n is 1 or 2.