Organic Light-Emitting Layer Using Exciplex Energy Transfer

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Solution Overview

Problem

Existing light-emitting elements using thermally activated delayed fluorescent materials face challenges in efficiently generating singlet excited states from triplet excited states, leading to low luminous efficiency, high drive voltage, and high power consumption.

Innovation Solution

A light-emitting element is designed with a light-emitting layer containing two organic compounds that form an exciplex, where one compound converts triplet excitation energy into light emission and another converts singlet excitation energy into light emission, optimizing energy transfer and reducing drive voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a thermally activated delayed fluorescent material is used to convert triplet excitation energy into light emission, then phosphorescence can be achieved, but the generation of singlet excited states from triplet excited states is inefficient leading to low luminous efficiency

Engineering Contradiction:

Improveluminous efficiencyVSAvoidgeneration efficiency of singlet excited states

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent introduces a fluorescent material as an intermediary substance that receives energy from the thermally activated delayed fluorescent material and converts it to light emission. This mediator enables efficient energy transfer and improves overall luminous efficiency by utilizing both singlet and triplet excited states through the fluorescent material's high quantum yield.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If a phosphorescent compound is used to convert triplet excitation energy into light emission, then higher luminous efficiency can be achieved, but the drive voltage becomes high and power consumption increases

Engineering Contradiction:

Improveluminous efficiencyVSAvoidpower consumption

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent changes the energy level parameters of the light-emitting layer by carefully selecting materials with specific HOMO and LUMO levels. The fluorescent material is chosen to have energy levels that match the thermally activated delayed fluorescent material, enabling efficient energy transfer at lower drive voltages and reducing power consumption while maintaining high luminous efficiency.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If a fluorescent compound is used instead of phosphorescent compound, then stability is improved, but the ability to convert triplet excitation energy into light emission is reduced

Engineering Contradiction:

Improvecompound stabilityVSAvoidtriplet excitation energy conversion

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent combines a thermally activated delayed fluorescent material (which can utilize triplet excited states) with a fluorescent material (which provides high stability and high quantum yield). This combination merges the advantages of both material types: the TADF material converts triplet states to singlet states, and the fluorescent material efficiently emits light from singlet states, achieving both stability and efficient triplet energy utilization.

Inventive Principle:

Principle #5Merging (Combining)

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 design enhances luminous efficiency, reduces drive voltage, and lowers power consumption while ensuring a highly reliable light-emitting element with a longer driving lifetime.

Implementation Method 1

The first organic compound and the second organic compound, in combination, are capable of forming an exciplex

Methodology Applied

Scientific EffectExciplex formation:

Implementation Method 2

One of the organic compounds has a function of converting triplet excitation energy into light emission

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 3

the third organic compound has a function of converting singlet excitation energy into light emission

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 4

excitation energy is supplied from the exciplex to the third organic compound

Methodology Applied

Scientific EffectEnergy transfer:

Data Source

PatentUS12480038B2Light-emitting element, display device, electronic device, and lighting device

Publication Date: 2025.11.25 SEMICON ENERGY LAB CO LTD

AI summary

A light-emitting element having high luminous efficiency is provided. The light-emitting element includes a first organic compound, a second organic compound, and a third organic compound. The first organic compound and the second organic compound, in combination, are capable of forming an exciplex. The first organic compound is a phosphorescent compound and the third organic compound is a fluorescent compound. Light emitted from the light-emitting element includes light emitted from the third organic compound to which excitation energy is supplied from the exciplex formed by the first organic compound and the second organic compound.