Nitrogen Heteropolyaromatic Acceptors for OLED Blue Emission

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Solution Overview

Problem

Current organic light-emitting diodes (OLEDs) face challenges in achieving high efficiency and stability for blue emission due to the limitations of electron delocalization in traditional electron acceptors, which affects the design of strong donor-acceptor strength and the stability of OLEDs incorporating triazene or cyano groups.

Innovation Solution

The use of nitrogen-containing dibenzofuran, dibenzothiophene, and dibenzoselenophene as high triplet energy heteropolyaromatic systems as electron acceptors in donor-acceptor compounds to enhance the efficiency of delayed fluorescence and blue emission in OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional electron acceptors with triazene or cyano groups are used in donor-acceptor compounds, then the design of strong donor-acceptor strength can be achieved, but the stability of OLEDs deteriorates

Engineering Contradiction:

Improvedonor-acceptor strengthVSAvoidstability of OLEDs

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical structure parameters of the electron acceptor by replacing traditional triazene or cyano groups with nitrogen-containing dibenzofuran, dibenzothiophene, and dibenzoselenophene heteropolyaromatic systems. This structural parameter change maintains strong donor-acceptor interaction while improving OLED stability, as these heteropolyaromatic systems provide both strong electron-accepting capability and enhanced device stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite donor-acceptor compounds where the acceptor component is a nitrogen-containing heteropolyaromatic system (dibenzofuran, dibenzothiophene, or dibenzoselenophene) combined with electron-donating groups. This composite material approach achieves both strong donor-acceptor strength and improved OLED stability by combining the electron-accepting properties of the heteropolyaromatic core with the electron-donating properties of attached groups.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If traditional electron acceptors are used in OLEDs, then the device structure can be simplified, but the internal quantum efficiency for blue emission deteriorates due to limitations in electron delocalization

Engineering Contradiction:

Improvedevice structureVSAvoidinternal quantum efficiency

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent changes the electronic structure parameters of the electron acceptor by using nitrogen-containing heteropolyaromatic systems with extended conjugation. This parameter change enhances electron delocalization across the molecule, improving internal quantum efficiency for blue emission while maintaining relatively simple device structure. The extended π-conjugation in dibenzofuran, dibenzothiophene, and dibenzoselenophene systems enables better charge transport and higher efficiency.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If strong donor-acceptor interaction is designed in OLED materials, then the efficiency of delayed fluorescence can be enhanced, but the stability of the materials deteriorates

Engineering Contradiction:

Improveefficiency of delayed fluorescenceVSAvoidstability of materials

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent designs composite donor-acceptor compounds where nitrogen-containing heteropolyaromatic acceptors (dibenzofuran, dibenzothiophene, or dibenzoselenophene) are combined with electron-donating groups. This composite structure achieves strong donor-acceptor interaction for high delayed fluorescence efficiency while the robust heteropolyaromatic core provides material stability, resolving the contradiction between efficiency and stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by concentrating the strong donor-acceptor interaction in specific molecular regions while maintaining stable structural frameworks. The nitrogen-containing heteropolyaromatic system provides a stable core structure, while the donor-acceptor interaction is localized between this stable core and the electron-donating groups, enabling high efficiency without sacrificing overall material stability.

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 proposed solution enables high efficiency delayed fluorescence OLEDs with improved stability and blue emission, exceeding the spin statistics limit for internal quantum efficiency, and demonstrates the potential for enhanced performance in organic light-emitting devices.

Implementation Method 1

Methodology Applied

Scientific EffectDelayed fluorescence: Fluorescence

Implementation Method 2

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9324949B2Organic electroluminescent materials and devices

Publication Date: 2016.04.26 UNIVERSAL DISPLAY CORP

AI summary

Luminescent materials including donor-acceptor compounds with a high triplet energy heteropolyaromatic system, namely, dibenzofuran, dibenzothiophene and dibenzoselenophene with one or multiple nitrogens in the ring as the electron acceptor for use as emitters in organic light emitting diodes is disclosed.