Polycyclic Boron Compound for TADF Emission Layer Efficiency

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Solution Overview

Problem

Current organic electroluminescence display devices face challenges in achieving high emission efficiency and long lifespan, particularly in utilizing energy from triplet states and delayed fluorescence phenomena effectively.

Innovation Solution

A light emitting element is designed with a specific polycyclic compound in the emission layer, comprising a first compound represented by Formula 1, and optionally including a second, third, and fourth compound, to enhance thermally activated delayed fluorescence and improve emission efficiency and lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional organic electroluminescence materials are used, then device structure is simple, but emission efficiency is low and lifespan is short

Engineering Contradiction:

Improveemission efficiencyVSAvoidemission layer composition

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The emission layer employs a composite material system comprising a host compound and a guest compound (polycyclic compound of Formula 1). This composite approach enables efficient energy transfer from the host to the guest, achieving high emission efficiency through synergistic material interaction while maintaining a relatively simple two-component structure.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The host compound acts as an intermediary that absorbs energy from electrical excitation and transfers it to the guest compound, which then emits light. This intermediary mechanism enables efficient energy utilization and extends device lifespan by preventing direct exciton accumulation in the emission layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If triplet state energy is utilized for phosphorescence emission, then emission efficiency increases, but device lifetime decreases due to exciton accumulation

Engineering Contradiction:

Improveemission efficiencyVSAvoiddevice lifetime

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The invention converts the potentially harmful triplet state excitons into beneficial delayed fluorescence emission. The polycyclic compound (Formula 1) exhibits thermally activated delayed fluorescence characteristics, transforming triplet excitons that would normally cause exciton accumulation and device degradation into useful light emission that extends device lifetime while maintaining high emission efficiency.

Inventive Principle:

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

3Productivity

If delayed fluorescence phenomenon is utilized, then emission efficiency improves, but manufacturing complexity increases

Engineering Contradiction:

Improveemission efficiencyVSAvoidemission layer fabrication

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The invention achieves delayed fluorescence by carefully selecting and optimizing the energy levels and molecular structures of the host and guest compounds. By controlling parameters such as triplet energy differences and molecular orientations, the system achieves efficient delayed fluorescence emission through a relatively simple two-component emission layer structure that can be manufactured using conventional organic electroluminescence fabrication processes.

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 solution achieves high emission efficiency and extended lifespan by utilizing the polycyclic compound in the emission layer, facilitating efficient energy transfer and reducing exciton accumulation, thereby improving the overall performance of the organic electroluminescence display device.

Implementation Method 1

a material having thermally activated delayed fluorescence (TADF) utilizing delayed fluorescence phenomenon is being intensively researched

Methodology Applied

Scientific EffectThermally activated delayed fluorescence: Phosphorescence

Implementation Method 2

delayed fluorescence emission that utilizes the generating phenomenon of singlet excitons by the collision of triplet excitons (triplet-triplet annihilation, TTA)

Methodology Applied

Scientific EffectTriplet-triplet annihilation:

Implementation Method 3

holes and electrons injected from a first electrode and a second electrode of the organic electroluminescence display device recombine in an emission layer of the organic electroluminescence display device so that a light emitting material in the emission layer emits light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20230320216A1Light emitting element and polycyclic compound for light emitting element

Publication Date: 2023.10.05 SAMSUNG DISPLAY CO LTD

AI summary

A light emitting element is provided to include a first electrode, a second electrode, and an emission layer disposed between the first electrode and the second electrode. The emission layer may include a polycyclic compound including a boron-containing core part and an electron donating group of a dibenzoheterole skeleton.