Pyrimidine-Coordinated Ligand Deepens HOMO Level in OLED Green Emitters

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Solution Overview

Problem

Conventional OLED devices have shallow HOMO levels in green emitters, leading to long electroluminescence transients, which affect the performance and efficiency of organic light-emitting diodes.

Innovation Solution

A compound with a pyrimidine-coordinated ligand is introduced, which deepens the HOMO level, addressing the issue by forming a metal complex that enhances the electroluminescence transient in OLED devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conventional green emitters are used in OLED devices, then the device can operate, but the HOMO level is shallow leading to long electroluminescence transients

Engineering Contradiction:

Improveelectroluminescence transient timeVSAvoidHOMO level depth

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent modifies the molecular structure of the green emitter by introducing a pyrimidine-coordinated ligand system, which changes the electronic parameters of the material. This structural parameter change results in a deeper HOMO level and shorter electroluminescence transient, directly resolving the technical contradiction between transient time and HOMO level depth.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the HOMO level is deepened to reduce transient time, then electroluminescence performance improves, but device complexity increases due to new ligand coordination requirements

Engineering Contradiction:

Improveelectroluminescence efficiencyVSAvoidligand coordination structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a composite ligand system combining pyrimidine coordination with additional ligands (such as C^N^C or C^N^C^N type ligands) to achieve the desired HOMO level deepening. This composite approach allows the complex electronic structure to be built from modular components, managing the complexity while achieving improved electroluminescence efficiency.

Inventive Principle:

Principle #40Composite materials

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 deepened HOMO level in the OLED devices results in improved electroluminescence performance by reducing the transient time, enhancing the overall efficiency and performance of the organic light-emitting diodes.

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

A compound with a pyrimidine-coordinated ligand is introduced, which deepens the HOMO level, addressing the issue by forming a metal complex that enhances the electroluminescence transient

Methodology Applied

Scientific EffectMetal complex formation: Chemical Bonding

Data Source

PatentUS20240279260A1Organic electroluminescent materials and devices

Publication Date: 2024.08.22 UNIVERSAL DISPLAY CORP

AI summary

A compound comprising a first ligand LA of Formula I,is provided. In Formula I, each of X1 to X6 is C or N; K is a direct bond, O, S, N(Rα), P(Rα), B(Rα), C(Rα)(Rβ), or Si(Rα)(Rβ); LA is coordinated to Ir through the indicated dashed lines; at least one of the following conditions is true: (1) R1 comprises at least five carbon atoms, and (2) two RB substituents are joined together to form a structure of Formula II,fused to ring B; X is CRX or N; Y is selected from a variety of linkers; each R, R′, R″, Rα, Rβ, RA, RB, RX, R1, and R2 is hydrogen or a General Substituent; and Ir may be coordinated to other ligands. Compositions, OLEDs, and consumer products including the compound are also provided.