OLED Metal Complex Ligands for Low-Voltage Blue Emission

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Solution Overview

Problem

Existing organic light-emitting diodes (OLEDs) face challenges with non-saturated blue color, short device lifetime, high operating voltage, and efficiency roll-off at high brightness, particularly in commercial full-color displays, with previous patents lacking detailed insights into the specific positions and lengths of substituents on ligands affecting device performance.

Innovation Solution

A series of metal complexes with a ligand structure represented by Formula 1, featuring specific substituents and bond lengths, are introduced to enhance device performance by reducing voltage, improving efficiency, and extending lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If phosphorescent emitters are used in OLEDs, then internal quantum efficiency is improved (achieving 100% IQE), but device lifetime is reduced and operating voltage increases

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent modifies the ligand structure by introducing specific substituents (Ra1, Ra2, Ra3) at defined positions on the aromatic rings, and controls the length of linker A (at least 6.7 Å) to optimize the metal complex properties. These parameter changes in molecular structure lead to improved device lifetime while maintaining high efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite ligand structures combining multiple aromatic rings (Cy1, Cy2), heterocyclic groups (X1-X7), and substituent groups (Ra1, Ra2, Ra3) coordinated with metal centers (M). This composite molecular design achieves both high efficiency and extended device lifetime by optimizing electronic properties and stability

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If phosphorescent emitters are used in OLEDs, then internal quantum efficiency is improved (achieving 100% IQE), but operating voltage increases

Engineering Contradiction:

Improveinternal quantum efficiencyVSAvoidoperating voltage

Core Design Contradiction:

Use of energy by moving objectVSStress or pressure

Solution Approach 1:

The patent optimizes the metal complex structure by selecting specific metals (M) with atomic number 21-30 and configuring the ligand La with specific substituent patterns and linker lengths. These parameter changes improve charge transport and reduce operating voltage while maintaining high internal quantum efficiency

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional ligand structures are used, then device fabrication is simpler, but color saturation and device performance are insufficient

Engineering Contradiction:

Improvefabrication simplicityVSAvoidcolor saturation

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces specific substituent groups (Ra1, Ra2, Ra3) at localized positions on the ligand structure, and defines specific linker length (A ≥ 6.7 Å) to achieve optimal color saturation and device performance while maintaining overall structural simplicity for fabrication

Inventive Principle:

Principle #3Local quality

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 novel metal complexes significantly improve the comprehensive performance of electroluminescent devices by enhancing color saturation, efficiency, and device lifetime.

Implementation Method 1

Organic light-emitting diodes (OLEDs)... Once a bias is applied to the device, green light was emitted from the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

Forrest and Thompson reported phosphorescent OLED, which uses triplet emission from heavy metal containing complexes as the emitter

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 3

triplet emission from heavy metal containing complexes as the emitter

Methodology Applied

Scientific EffectHeavy metal effect:

Implementation Method 4

Adachi achieved high efficiency through thermally activated delayed fluorescence (TADF) of organic compounds. These emitters have small singlet-triplet gap that makes the transition from triplet back to singlet possible

Methodology Applied

Scientific EffectThermally activated delayed fluorescence:

Data Source

PatentUS12552821B2Organic electroluminescent material and device thereof

Publication Date: 2026.02.17 BEIJING SUMMER SPROUT TECH CO LTD

AI summary

Provided are an organic electroluminescent material and a device thereof. The organic electroluminescent material is a metal complex including a ligand La having a structure of Formula 1, and the metal complex can be used as luminescent materials in electroluminescent devices. These new compounds, when used in electroluminescent devices, can show better performance, provide lower device voltage and higher device efficiency, and significantly improve the comprehensive performance of devices. Further provided are an electroluminescent device including the metal complex and a compound composition including the metal complex.