LED Reflective Layer Structure for Short-Wave Light Extraction

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Solution Overview

Problem

The existing LED technologies face challenges in achieving high light extraction efficiency due to the poor reflectivity of silver in the short-wave band and light absorption by the adhesion layer, leading to reduced luminous efficiency.

Innovation Solution

The use of aluminum as the reflective layer, which provides high reflectivity in the short-wave band, eliminates the need for an adhesion layer, reduces light absorption, and enhances the reflection effect by forming a flat surface through through holes, thereby improving light-emitting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If silver is used as the reflective electrode to form a current blocking layer, then the adhesion between layers is improved, but the reflectivity in the short-wave band drops sharply

Engineering Contradiction:

Improveadhesion between layersVSAvoidreflectivity in short-wave band

Core Design Contradiction:

StrengthVSIllumination intensity

Solution Approach 1:

The patent changes the material parameter of the reflective layer from silver to aluminum, which fundamentally alters the optical properties. Aluminum maintains high reflectivity in the short-wave band (including UV region) unlike silver whose reflectivity drops sharply below 365nm. This material substitution resolves the contradiction by selecting a material whose inherent properties satisfy both adhesion requirements and short-wave reflectivity requirements.

Inventive Principle:

Principle #35Parameter changes

2Strength

If an adhesion layer is added between silver and the current blocking layer, then the adhesion is improved, but light absorption increases and luminous efficiency reduces

Engineering Contradiction:

ImproveadhesionVSAvoidlight absorption

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent extracts and eliminates the adhesion layer from the structure by using aluminum as the reflective electrode material. Since aluminum inherently forms good adhesion with the current blocking layer without requiring an additional adhesion layer, this removal eliminates the source of light absorption while maintaining structural integrity. The solution takes out the problematic intermediate layer that caused energy loss.

Inventive Principle:

Principle #2Taking out (Extraction)

3Illumination intensity

If aluminum is used as the reflective layer, then the reflectivity in the short-wave band is improved, but the adhesion between aluminum and current blocking layer needs to be ensured

Engineering Contradiction:

Improvereflectivity in short-wave bandVSAvoidadhesion between aluminum and current blocking layer

Core Design Contradiction:

Illumination intensityVSStrength

Solution Approach 1:

The patent applies self-service principle where the aluminum layer itself provides both the reflective function and the adhesion function. Aluminum naturally forms a protective oxide layer on its surface that enhances adhesion to the current blocking layer, eliminating the need for separate adhesion promotion treatments. The material serves multiple functions simultaneously, resolving the contradiction between achieving high reflectivity and ensuring adequate adhesion.

Inventive Principle:

Principle #25Self-service

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 solution increases light reflection and reduces light absorption, resulting in improved light-emitting efficiency and display effects for LED chips by using aluminum reflective layers without silver, which prevents Ag migration and allows for a larger reflective area.

Implementation Method 1

metal Al has high reflectivity in a short-wave band, so that the reflection of light radiated by the active layer can be increased

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

there is no problem of light absorption by the adhesion layer

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS20240405163A1Light-emitting diode and light-emitting device

Publication Date: 2024.12.05 XIAMEN SANAN OPTOELECTRONICS CO LTD

AI summary

A light-emitting diode and a light-emitting device are provided. A transparent conductive layer, a current blocking layer and a first metal reflective layer are sequentially arranged on a side of a second semiconductor layer away from an active layer. A side of the first metal reflective layer adjacent to the current blocking layer is a first Al reflective layer, and metal Al has high reflectivity in a short-wave band, increasing the reflection of light radiated by the active layer. Since there is no need to form an adhesion layer between the first Al reflective layer and the current blocking layer, there is no light absorption problem of the adhesion layer. A projection area of the first metal reflective layer is greater than or equal to that of the transparent conductive layer, so that the first metal reflective layer can cover a larger light-emitting surface, thereby further improving the light reflection.