Aluminum Reflective Layer Oxidation for OLED Surface Defects

Solution Overview

Problem

The existing OLED manufacturing processes face challenges with the formation of concavities and hillocks on the surface of aluminum films, leading to reduced reflectivity and increased manufacturing costs due to the use of Ag, and existing solutions do not effectively address these issues.

Innovation Solution

A method involving the formation of a bottom ITO layer, followed by a uniform aluminum oxide layer created by introducing oxygen gas, and a top ITO layer, which adjusts coating velocity and refractive index to enhance the reflectivity of the aluminum layer, thereby improving the surface smoothness and reducing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If Ag is used as the reflective material, then the reflectivity is high and color-adjustment is controllable, but the manufacturing cost increases by 2 to 3 times

Engineering Contradiction:

ImprovereflectivityVSAvoidmanufacturing cost

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive Ag target materials with inexpensive Al target materials. Although Al has lower inherent reflectivity, the addition of oxide layer treatment makes it a cost-effective substitute that maintains adequate optical performance while dramatically reducing material costs.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the surface state of Al by forming an oxide layer and controlling its thickness (5-50 nm). This parameter change transforms Al from a material with insufficient reflectivity to one that achieves the required optical performance, making it a viable alternative to Ag.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If Al is used as the reflective material, then the manufacturing cost is reduced and processing is mature, but the reflectivity is lower and surface defects such as concavities and hillocks occur

Engineering Contradiction:

Improvemanufacturing costVSAvoidreflectivity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent changes the surface state of Al by forming an oxide layer and controlling its thickness (5-50 nm). This parameter change transforms Al from a material with insufficient reflectivity to one that achieves the required optical performance, making it a viable alternative to Ag.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary oxidation of the Al surface before the Al layer is fully formed or shortly after formation. This preliminary action of creating the oxide layer in advance prevents surface defects and enhances reflectivity before subsequent processing steps.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If Al is used as the reflective material, then the manufacturing cost is reduced, but concavities and hillocks are formed on the surface reducing film quality

Engineering Contradiction:

Improvemanufacturing costVSAvoidsurface quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs preliminary oxidation of the Al surface before the Al layer is fully formed or shortly after formation. This preliminary action of creating the oxide layer in advance prevents surface defects and enhances reflectivity before subsequent processing steps.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The oxide layer acts as an intermediary between the Al layer and the subsequent processing steps. It serves as a protective and smoothing layer that prevents the formation of concavities and hillocks, improving surface quality.

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 method improves the reflectivity of the aluminum layer by 2-3% and reduces concavities and hillocks, enhancing the controllability of OLED color-adjustment and surface quality.

Implementation Method 1

The reflective layer reflects radiation from the organic layer toward the transparent second electrode

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

forming an aluminum oxide layer on a surface of the aluminous reflective layer uniformly by introducing plenty of oxygen gas simultaneously

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS9437836B2Method for improving the reflectivity of aluminum in OLED structure

Publication Date: 2016.09.06 EVERDISPLAY OPTRONICS (SHANGHAI) CO LTD

AI summary

The present disclosure discloses a method for improving the reflectivity of aluminum in OLED structure. The OLED structure includes a top ITO layer, a middle reflective layer made by aluminum and a bottom ITO layer. The method comprises; forming a bottom ITO layer; coating the aluminous reflective layer on the surface of the bottom ITO layer and forming an aluminum oxide layer on the surface of the aluminous reflective layer uniformly by introducing plenty of oxygen gas simultaneously; adjusting the velocity of coating the aluminous reflective until the aluminum oxide layer is formed; and forming an top ITO layer on the surface of the aluminum oxide layer. The present disclosure can repair and cover the defects on the surface of the metal aluminum film and can reduce the concavities and hillocks on the surface of the metal aluminum film. Consequently, the reflectivity of aluminum in OLED structure is improved.