OLED Pad Electrode Redox Barrier for Silver Particle Defects
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Solution Overview
Problem
Large-screen organic light-emitting display apparatuses face challenges with voltage drops and particle defects due to the increased thickness of electrodes and wirings, which can lead to re-precipitation of silver particles during the etching process, causing short circuits and breakage of insulating layers.
Innovation Solution
The organic light-emitting display apparatus employs a dual or triple structure for pixel electrodes and pad layers, using materials with high and low reducibility, such as silver and copper, and includes transparent conductive oxide layers to prevent particle defects and voltage drops, while also using a light adjusting layer with varying thicknesses to enhance light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of electrodes and wirings is increased in large-screen organic light-emitting display apparatuses, then voltage drops are reduced, but particle defects occur due to re-precipitation of silver particles during the etching process
Solution Approach 1:
The pixel electrode is divided into multiple layers: a first pixel electrode layer containing silver (high reducibility) and a second pixel electrode layer containing copper or aluminum alloy (low reducibility). This segmentation allows the lower reducibility material to prevent silver particle re-precipitation during etching while the overall electrode thickness is maintained to reduce voltage drops.
Solution Approach 2:
A barrier layer containing material with low reducibility (copper or aluminum alloy) is introduced as an intermediary between the silver-containing electrode layer and the etching environment. This barrier layer mediates the etching process by preventing silver ions from re-precipitating as particles while allowing the etching to proceed for pattern formation.
2Loss of energy
If silver material is used in pixel electrodes to improve conductivity, then voltage drops are reduced, but silver particles re-precipitate during etching causing short circuits
Solution Approach 1:
A barrier layer containing material with low reducibility (copper or aluminum alloy) is introduced as an intermediary between the silver-containing electrode layer and the etching environment. This barrier layer mediates the etching process by preventing silver ions from re-precipitating as particles while allowing the etching to proceed for pattern formation.
Solution Approach 2:
The pixel electrode is formed as a composite structure combining silver (for high conductivity) with copper or aluminum alloy (for low reducibility and particle prevention). This composite material approach allows simultaneous achievement of low voltage drop and prevention of silver particle re-precipitation during etching.
3Loss of energy
If thicker electrodes are used to reduce voltage drops, then conductivity is improved, but manufacturing complexity increases due to multi-layer structures
Solution Approach 1:
The function of preventing silver particle re-precipitation is extracted from the silver electrode material itself and assigned to a separate barrier layer. This allows the silver layer to focus on providing conductivity while the barrier layer handles the particle prevention function, simplifying the overall manufacturing process despite the multi-layer structure.
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 allows for thicker electrodes and wirings without particle defects, reducing voltage drops and improving light efficiency through resonance phenomena, while preventing material oxidation and diffusion.
Implementation Method 1
a third pad layer which is disposed between the first pad layer and the second pad layer and contains a material having a reducibility that is lower than a reducibility of a material contained in the second pad layer
Implementation Method 2
Holes injected from the hole injection electrode and electrons injected from the electron injection electrode are recombined and dissipated at the organic light emitting layer to emit light
Implementation Method 3
A plurality of light adjusting layers, which are respectively disposed at different pixels among the plurality of pixels, have different thicknesses
Data Source
AI summary
Disclosed is an organic light-emitting display apparatus. The organic light-emitting display apparatus includes a pixel electrode that is connected to at least one thin film transistor, an opposite electrode that is disposed to face the pixel electrode, an organic light emitting layer that is disposed between the pixel electrode and the opposite electrode, and a pad electrode that includes a first pad layer, a second pad layer disposed on the first pad layer, and a third pad layer which is disposed between the first pad layer and the second pad layer and contains a material having a reducibility that is lower than a reducibility of a material contained in the second pad layer.