Organic Electroluminescent Device Light Extraction Efficiency

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Solution Overview

Problem

Organic electroluminescent devices face low light extraction efficiency due to total reflection at interfaces with different refractive indices, requiring multiple light-extracting units that complicate design and increase costs, and existing light-extracting units like lenses, prisms, and fine particle layers do not achieve 100% efficiency.

Innovation Solution

An organic electroluminescent device configuration with a unified light-extracting unit combining a prism array as the light-extracting member and a fine particle layer as the light distribution-converting member, placed on a transparent substrate to minimize total reflection interfaces and optimize light extraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multiple light-extracting units are provided at different interfaces to improve light extraction efficiency, then light extraction efficiency is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoiddevice complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines multiple light-extracting units (prism array and fine particle layer) into a single integrated structure placed at one interface (the interface between transparent substrate and air). This merging approach maintains the light extraction benefits of multiple units while reducing device complexity and manufacturing cost by eliminating the need for separate units at multiple interfaces.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a new dimension by placing light-extracting units in a fine particle layer that can be positioned at a specific distance from the organic electroluminescent layer. This spatial arrangement in three-dimensional space allows optimized light extraction without requiring multiple interfaces, thereby reducing complexity while maintaining efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of energy

If multiple light-extracting units are provided to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing cost increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent merges multiple light-extracting functions into a single integrated structure, reducing the number of manufacturing steps and assembly operations required. This approach maintains high light extraction efficiency while significantly reducing manufacturing cost and complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If light-extracting units are provided at multiple interfaces, then light extraction efficiency is improved, but the number of total reflection interfaces increases

Engineering Contradiction:

Improvelight extraction efficiencyVSAvoidtotal reflection interfaces

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a fine particle layer as an intermediary medium between the organic electroluminescent layer and the air. This intermediary layer with optimized refractive index reduces total reflection at the interface, allowing more light to be extracted without requiring multiple light-extracting units at different interfaces, thereby reducing the number of harmful reflection interfaces.

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

This configuration enhances external light extraction efficiency, reduces power consumption, and prolongs device service life by minimizing the number of interfaces where total reflection occurs and optimizing light distribution.

Implementation Method 1

when light is emitted at an angle equal to or higher than a critical angle determined based on the refractive index of the organic electroluminescent layer and the refractive index of a medium into which the light is to be emitted, the light cannot be emitted to the air, totally reflected, and confined in the interior of the organic electroluminescent layer

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

the light cannot be emitted to the air, totally reflected, and confined in the interior of the organic electroluminescent layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

the distribution of light emitted from the organic electroluminescent layer is a Lambertian distribution

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS10734610B2Organic electroluminescent device

Publication Date: 2020.08.04 UDC IRELAND

AI summary

[Problem] To provide an organic electroluminescent device that is excellent in external extraction efficiency of emitted light and able to attain reduced power consumption and prolonged service life.[Solution] An organic electroluminescent device including, in an order mentioned: a reflective electrode; an organic electroluminescent layer; a transparent substrate; and a light-extracting unit, wherein the light-extracting unit contains a light-extracting member and a light distribution-converting member. In one preferable embodiment, the light-extracting member and the light distribution-converting member are each a prism, a prism array, a lens, a lens array, a fine concavo-convex structure or a fine particle layer.