Organometallic Compound for OLED Emission Layer Efficiency

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Solution Overview

Problem

Organic light-emitting devices (OLEDs) face challenges in achieving low driving voltage, high emission efficiency, and long lifespan due to internal energy issues within the molecules, leading to suppressed non-emission transitions during intramolecular energy transfer.

Innovation Solution

An organometallic compound with a novel structure, represented by Formula 1, is integrated into the emission layer of OLEDs, reducing internal energy and increasing molecular stability, which enhances emission efficiency and extends device lifespan by facilitating efficient energy transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional organic compounds are used in OLED emission layers, then device structure is simple, but emission efficiency is low and lifespan is short due to internal energy issues and non-emission transitions

Engineering Contradiction:

Improveemission efficiencyVSAvoidmolecular structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs organometallic compounds comprising metal centers (iridium, platinum, or copper) coordinated with organic ligands containing specific heterocyclic structures (triazole, tetrazole, or pyrazole rings). This composite molecular architecture combines the benefits of metal-based phosphorescent emitters with stabilized organic frameworks, achieving high emission efficiency while maintaining structural manageability through deliberate molecular design.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention systematically varies key molecular parameters including metal center selection (Ir, Pt, Cu), ligand types (carboxylate, heterocyclic aromatic), and substituent positions to optimize the balance between emission efficiency and molecular stability. By controlling molecular weight ranges (500-2000 Da) and adjusting heteroatom compositions, the patent achieves enhanced photostability and reduced non-emission transitions without excessive structural complexity.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If molecules with high internal energy are used, then energy transfer is active, but non-emission transitions occur reducing emission efficiency

Engineering Contradiction:

Improveenergy transfer efficiencyVSAvoidemission efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent converts potentially harmful high internal energy that causes non-emission transitions into beneficial sustained energy transfer by incorporating heavy metal atoms (iridium, platinum, copper) with high atomic numbers. These metal centers introduce spin-orbit coupling that enables efficient intersystem crossing to triplet states, transforming energy that would otherwise be lost through non-radiative pathways into useful phosphorescent emission, achieving both active energy transfer and high emission efficiency.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If molecular stability is increased to suppress non-emission transitions, then emission efficiency improves, but driving voltage increases

Engineering Contradiction:

Improveemission efficiencyVSAvoiddriving voltage

Core Design Contradiction:

ProductivityVSPower

Solution Approach 1:

The patent applies local quality optimization by introducing electron-donating and electron-withdrawing groups at specific positions on the ligand framework. This creates localized electron density variations that facilitate charge injection and transport at critical interfaces while maintaining overall molecular stability. The heterocyclic ligands with nitrogen and oxygen atoms provide localized sites for efficient charge transfer, reducing driving voltage requirements without compromising the global molecular stability needed for high emission efficiency.

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 organometallic compound in the OLEDs results in low driving voltage, high emission efficiency, and extended lifespan by reducing internal energy and suppressing non-emission transitions, leading to improved light-emission quantum efficiency and energy transfer efficiency.

Implementation Method 1

suppression of non-emission transition during intramolecular energy transfer

Methodology Applied

Scientific EffectIntramolecular energy transfer:

Implementation Method 2

Carriers, such as holes and electrons, recombine in the emission layer to produce excitons. These excitons transition from an excited state to a ground state to thereby generate light.

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20220131095A1Organometallic compound and an organic light-emitting device including the same

Publication Date: 2022.04.28 SAMSUNG DISPLAY CO LTD

AI summary

A light-emitting device includes: a first electrode; a second electrode; an interlayer between the first electrode and the second electrode and including an emission layer; and an organometallic compound represented by Formula 1, as defined herein.