Multicolor Light-Emitting Layer Structure With Exciplex Energy Transfer

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Solution Overview

Problem

Existing multicolor light-emitting elements using fluorescence and phosphorescence have limitations in manufacturing complexity, efficiency, and cost due to the need for multiple layers, which hinders practical application and increases power consumption.

Innovation Solution

A light-emitting element with a stacked-layer structure comprising a first exciplex layer and a phosphorescent layer, where the exciplex is formed by a combination of organic compounds with close singlet and triplet excited levels, allowing for efficient energy transfer and reduced layer complexity, thereby enhancing emission efficiency and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multiple layers are used to achieve multicolor light emission, then emission efficiency is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveemission efficiencyVSAvoidlayer structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines fluorescence and phosphorescence emission mechanisms into a single integrated light-emitting layer, eliminating the need for separate fluorescent and phosphorescent layers. This merging approach maintains multicolor emission capability while reducing structural complexity and manufacturing cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The light-emitting layer is designed to perform multiple functions simultaneously: it generates both fluorescent and phosphorescent emission, achieves color tuning capability, and maintains high emission efficiency. The exciplex system enables the layer to function as both a fluorescent emitter and a phosphorescence host, reducing the need for additional specialized layers.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of energy

If multiple layers are used to achieve multicolor light emission, then emission efficiency is improved, but manufacturing cost increases

Engineering Contradiction:

Improveemission efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional fluorescent substances are used, then manufacturing is simpler, but emission efficiency is limited to 25%

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidinternal quantum efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent introduces an exciplex system as an intermediary between the fluorescent host and phosphorescent dopant. The exciplex acts as a energy transfer mediator that enables efficient population of triplet states, which then transfer energy to the phosphorescent dopant. This intermediary mechanism overcomes the 25% efficiency limit of conventional fluorescent materials while maintaining manufacturing simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light-emitting layer uses a composite material system consisting of a fluorescent host compound, a phosphorescent dopant, and forms an exciplex complex. This composite approach combines the manufacturing advantages of fluorescent materials with the high efficiency of phosphorescence, achieving internal quantum efficiency exceeding 25% while maintaining ease of fabrication.

Inventive Principle:

Principle #40Composite materials

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 enables a multicolor light-emitting element with improved emission efficiency, reduced power consumption, and lower manufacturing costs by simplifying the layer structure while maintaining high emission performance.

Implementation Method 1

the exciplex is formed by a combination of organic compounds with close singlet and triplet excited levels, allowing for efficient energy transfer

Methodology Applied

Scientific EffectEnergy transfer:

Implementation Method 2

a second light-emitting layer exhibiting phosphorescence... a phosphorescent substance... light emission from the triplet excited state (phosphorescence)

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS11937439B2Light-emitting element, light-emitting device, display device, electronic appliance, and lighting device

Publication Date: 2024.03.19 SEMICON ENERGY LAB CO LTD

AI summary

A multicolor light-emitting element using fluorescence and phosphorescence, which has a small number of manufacturing steps owing to a relatively small number of layers to be formed and is advantageous for practical application can be provided. In addition, a multicolor light-emitting element using fluorescence and phosphorescence, which has favorable emission efficiency is provided. A light-emitting element which includes a light-emitting layer having a stacked-layer structure of a first light-emitting layer exhibiting light emission from a first exciplex and a second light-emitting layer exhibiting phosphorescence is provided.