Amide Carbene OLED Emitters for Stable Blue Emission

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Solution Overview

Problem

Blue-emitting materials for OLEDs face challenges due to high energy requirements leading to detrimental photophysical processes and chemical decomposition, with existing heavy-metal phosphors and thermally activated delayed fluorescence alternatives failing to achieve sufficient emission lifetimes.

Innovation Solution

A compound of formula (I) is introduced, comprising a metal, carbene ligand, and amide ligand structures, which can be used in an organic layer of OLEDs to enhance emission efficiency and stability, potentially overcoming the limitations of current blue-emitting materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If heavy-metal phosphors are used for blue emission, then radiative rate is improved, but emission lifetime becomes too short (below 1 μs)

Engineering Contradiction:

Improveradiative rateVSAvoidemission lifetime

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The patent changes the fundamental emission mechanism parameter from phosphorescence (heavy-metal based) to thermally activated delayed fluorescence (TADF). This parameter change allows the emission lifetime to extend beyond 1 μs while maintaining high radiative rates through optimized singlet-triplet energy separation (ΔEST) and enhanced spin-orbit coupling effects, thus resolving the contradiction between radiative rate and emission lifetime.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite emissive materials combining organic host matrices with TADF emitters that incorporate specific molecular structures (e.g., carbazole, triphenamine derivatives). This composite approach enables simultaneous achievement of long emission lifetime (>1 μs) and high radiative rates through synergistic effects of the host-guest system, overcoming the limitations of pure heavy-metal phosphors.

Inventive Principle:

Principle #40Composite materials

2Duration of action of moving object

If early developed TADF materials are used, then emission lifetime is extended, but radiative rate becomes too slow due to long-lived excitons

Engineering Contradiction:

Improveemission lifetimeVSAvoidradiative rate

Core Design Contradiction:

Duration of action of moving objectVSSpeed

Solution Approach 1:

The patent optimizes the ΔEST parameter (singlet-triplet energy separation) to a specific range that enables fast reverse intersystem crossing while maintaining long emission lifetime. By carefully tuning molecular structures to achieve ΔEST values that balance exciton lifetime and radiative rate, the patent resolves the contradiction between extended emission lifetime and sufficient radiative rate in TADF materials.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If high energy is used for blue emission, then emission wavelength is improved, but detrimental photophysical processes and chemical decomposition increase

Engineering Contradiction:

Improveemission wavelengthVSAvoidchemical stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent introduces TADF emitters as intermediary species that absorb high-energy excitons and transfer energy to lower-energy emitting states through thermal activation. This intermediary mechanism allows blue emission at desired wavelengths while reducing direct high-energy excitation damage to the material, thereby improving chemical stability and reducing detrimental photophysical processes like triplet-triplet annihilation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 compound improves emission efficiency and stability, addressing the issues of short lifetimes and chemical decomposition in blue-emitting OLEDs, enabling higher performance in display technologies.

Implementation Method 1

facilitating high photoluminescence efficiency through intramolecular charge transfer transitions

Methodology Applied

Scientific EffectIntramolecular charge transfer:

Implementation Method 2

rapid intersystem crossing, enabling efficient emission from excited states

Methodology Applied

Scientific EffectIntersystem crossing:

Implementation Method 3

thermally activated delayed fluorescence, addressing the limitations of existing blue-emitting materials

Methodology Applied

Scientific EffectThermally activated delayed fluorescence:

Data Source

PatentUS12617806B2Organic electroluminescent materials and devices

Publication Date: 2026.05.05 UNIV OF SOUTHERN CALIFORNIA

AI summary

The present disclosure provides amide M carbene emitters of Formula (I); organic light emitting device (OLED) comprising an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound of Formula (1); and consumer products comprising an OLED comprising a compound of Formula (I):