Barrier Layer for Display Pixel Electrode Metal Diffusion
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Solution Overview
Problem
During the manufacturing process of display apparatuses, metal can flow out from the pixel electrode, leading to defects in light-emitting elements, which increases the defect rate.
Innovation Solution
Incorporating a reflective layer with a first metal, such as aluminum, and a transparent layer with a transparent conductive oxide, along with a barrier layer made of an oxide of a second metal, like titanium, between the reflective and transparent layers to prevent metal diffusion and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a pixel electrode is formed with a reflective layer including aluminum or aluminum alloy, then the light efficiency and reflectivity are improved, but metal flows out during manufacturing causing defects in light-emitting elements
Solution Approach 1:
A barrier layer comprising an oxide of a second metal (different from the first metal in the reflective layer) is introduced between the reflective layer and the transparent layer. This intermediary barrier layer prevents metal diffusion from the reflective layer to the transparent layer and opposite electrode, thereby reducing defects while maintaining the light efficiency provided by the aluminum-based reflective layer.
2Reliability
If a barrier layer is added between the reflective layer and transparent layer to prevent metal diffusion, then the defect rate is reduced, but the device structure becomes more complex
Solution Approach 1:
The barrier layer is designed with specific thickness parameters (about 5 Å to about 100 Å) and material composition (oxide of second metal) that optimize its protective function while minimizing its impact on overall device complexity. The thickness is sufficient to prevent metal diffusion but thin enough to maintain light efficiency.
3Use of energy by moving object
If the reflective layer thickness is increased to improve reflectivity, then light efficiency is improved, but metal loss and defects increase during manufacturing
Solution Approach 1:
The barrier layer acts as a protective intermediary that contains the reflective layer metal, preventing its diffusion into the transparent layer and opposite electrode. This allows the reflective layer to maintain optimal thickness for light efficiency without excessive metal loss during manufacturing and operation.
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 effectively reduces the defect rate of light-emitting elements by preventing metal diffusion during the manufacturing process, maintaining reflectivity and light efficiency while minimizing material loss.
Implementation Method 1
a first barrier layer disposed between the reflective layer and the transparent layer. The first barrier layer includes an oxide of a second metal different from the first metal
Implementation Method 2
forming a barrier layer by oxidizing at least a portion of the metal thin film
Data Source
AI summary
For a display apparatus with a reduced defect rate and a method of manufacturing the display apparatus, the display apparatus includes: a pixel electrode; an opposite electrode disposed on the pixel electrode; and an intermediate layer disposed between the pixel electrode and the opposite electrode, wherein the pixel electrode includes: a reflective layer including a first metal; a transparent layer disposed on the reflective layer; and a first barrier layer disposed between the reflective layer and the transparent layer. The first barrier layer includes an oxide of a second metal different from the first metal.