Organic Insulating Layer Adhesion via Intermediate Oxide Barrier
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Solution Overview
Problem
Conventional organic electroluminescence display panels face issues with peeling of the organic insulating layer from the second conductive layer and increased contact resistance due to the transformation of aluminium or aluminium alloy in the second conductive layer into aluminium oxide when in contact with indium tin oxide, leading to low conductivity.
Innovation Solution
Incorporating an intermediate layer made of an oxide or nitride between the second conductive layer and the inner circumferential face of the organic insulating layer, which enhances adhesion and prevents the transformation of the second conductive layer into aluminium oxide, maintaining direct contact and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminium or aluminium alloy is used as the second conductive layer to save costs, then manufacturing cost is reduced, but the aluminium atoms transform into aluminium oxide when in contact with oxygen atoms in the intermediate layer, increasing contact resistance
Solution Approach 1:
A tungsten layer is introduced as an intermediary between the aluminium-based second conductive layer and the indium tin oxide intermediate layer. This tungsten barrier layer prevents direct contact between aluminium and oxygen, stopping the formation of aluminium oxide and maintaining low contact resistance while allowing the cost-effective aluminium material to be used
Solution Approach 2:
The tungsten layer is placed in advance between the aluminium conductive layer and the oxygen-containing intermediate layer to preemptively prevent the harmful oxidation reaction before it can occur, thereby maintaining the electrical conductivity of the aluminium layer
2Strength
If the intermediate layer is formed across the entire boundary between the first conductive layer and the second conductive layer, then adhesion is improved, but the second conductive layer transforms into aluminium oxide at the bottom face of the aperture, increasing contact resistance
Solution Approach 1:
The intermediate layer is selectively formed only on the inner circumferential face of the aperture in the organic insulating layer, not on the bottom face. This localized approach provides adhesion where needed while preventing aluminium oxidation at the contact area, achieving both goals simultaneously
Solution Approach 2:
The intermediate layer is segmented into different regions: present on the inner circumferential face for adhesion, and absent on the bottom face to prevent oxidation. This segmentation allows different functional requirements to be satisfied in different locations
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 prevents peeling of the organic insulating layer and constrains contact resistance, ensuring reliable electrical conductivity and device stability by using high-adhesion materials like oxides or nitrides between the conductive layers.
Implementation Method 1
metallic oxide material is known to have high adhesion, with respect to organic material as well as metallic material. As such, there is high adhesion between the organic insulating layer 921 and the intermediate layer 935, and high adhesion between the intermediate layer 935 and the second conductive layer 923
Implementation Method 2
a portion of the second conductive layer that is in contact with the intermediate layer is at risk of transformation into aluminium oxide. This is because the high bonding strength of aluminium atoms to oxygen atoms makes, for example, the aluminium atoms in the second conductive layer prone to reacting with the oxygen atoms in the indium tin oxide of the intermediate layer
Implementation Method 3
a light-emitting element has been developed that emits light upon being supplied with electric current in a forward direction. Such light-emitting elements include an organic electroluminescence element (hereinafter also organic EL element), which employs the organic material electroluminescence effect of organic fluorescent materials to produce light
Data Source
AI summary
An electronic device includes a substrate, a first conductive layer disposed over the substrate, an organic insulating layer, including an organic material, disposed over the first conductive layer and having an aperture exposing a portion of the first conductive layer, a second conductive layer, which is metallic, covering a top face of the organic insulating layer, an inner circumferential face that faces the aperture in the organic insulating layer, and the exposed portion of the first conductive layer, and an intermediate layer that includes an oxide or a nitride, disposed only between the second conductive layer and the inner circumferential face that faces the aperture in the organic insulating layer. The first conductive layer and the second conductive layer are in contact at the bottom face of the aperture in the organic insulating layer.