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 efficiency, high brightness, and long lifespan.

Innovation Solution

An organometallic compound represented by Formula 1 is used in the emission layer of OLEDs, acting as a dopant to improve driving voltage, current density, external quantum luminescence efficiency, roll-off ratio, and lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional phosphorescent luminescent compounds are used in OLEDs, then light emission is achieved, but driving voltage remains high and efficiency is limited

Engineering Contradiction:

Improvedriving voltageVSAvoiddevice performance stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent modifies the molecular structure of phosphorescent luminescent compounds by introducing specific substituents (R1-R6 groups) and coordinating metal centers (Ir, Pt, Os) to change electronic and steric parameters. This structural parameter optimization enables lower driving voltage while maintaining stable device performance through improved charge transport and reduced molecular aggregation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates composite luminescent materials by combining organic ligands with heavy metal centers (Ir, Pt, Os) to form organometallic complexes. This composite structure integrates the benefits of organic materials (processability, tunability) with metal centers (high quantum yield, long phosphorescence lifetime), achieving both low driving voltage and high efficiency.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If OLEDs operate at high brightness, then illumination intensity increases, but efficiency rolls off and lifespan decreases

Engineering Contradiction:

ImprovebrightnessVSAvoidluminescence efficiency

Core Design Contradiction:

Illumination intensityVSProductivity

Solution Approach 1:

The patent introduces specific substituent groups (R1-R6) at strategic positions on the ligand framework to create local electronic and steric environments that prevent molecular aggregation and reduce triplet-triplet annihilation. This local structural optimization maintains high luminescence efficiency even at high brightness levels by controlling intermolecular interactions in the emission zone.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention utilizes the heavy atom effect of metal centers (Ir, Pt, Os) to enhance spin-orbit coupling, which converts harmful non-radiative decay pathways into useful phosphorescence emission. This converts what would be energy loss into beneficial light emission, maintaining high efficiency at high brightness through enhanced radiative decay rates.

Inventive Principle:

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

3Illumination intensity

If OLEDs operate at high brightness, then illumination intensity increases, but lifespan is reduced

Engineering Contradiction:

ImprovebrightnessVSAvoiddevice lifespan

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent incorporates bulky substituent groups (R1-R6) and rigid ligand frameworks that preemptively prevent molecular aggregation and degradation pathways before they can occur during device operation. This structural cushioning protects the luminescent centers from degradation even under high brightness stress, extending device lifespan.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Use of energy by moving object

If conventional luminescent compounds are used, then light emission is achieved, but external quantum luminescence efficiency is limited

Engineering Contradiction:

Improveexternal quantum luminescence efficiencyVSAvoidenergy loss in emission

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent optimizes the metal-to-ligand charge transfer (MLCT) and ligand-to-ligand charge transfer (LLCT) parameters by selecting specific metal centers and ligand combinations. This parameter optimization enhances radiative decay rates and quantum yields, minimizing energy loss and maximizing external quantum luminescence efficiency through tailored electronic structures.

Inventive Principle:

Principle #35Parameter changes

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 enhances the performance of OLEDs by reducing driving voltage, improving current density, external quantum luminescence efficiency, and extending lifespan while maintaining excellent electric and thermal stability.

Implementation Method 1

An example of these luminescent compounds is a phosphorescent luminescent compound

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

The holes and the electrons recombine in the emission layer to produce excitons. These excitons transit from an excited state to a ground state, thereby generating light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11459348B2Organometallic compound, organic light-emitting device including the same, and diagnostic composition including the organometallic compound

Publication Date: 2022.10.04 SAMSUNG ELECTRONICS CO LTD

AI summary

An organometallic compound represented by Formula 1:wherein, in Formula 1, R1 to R12 and R16 are the same as described in the specification.