OLED Pixel Structure with Auxiliary Electrode for Voltage Drop Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix organic light-emitting display devices suffer from poor brightness uniformity due to voltage drop effects, particularly in large-sized displays, where the use of certain metals or transparent conductive oxides as upper electrodes exacerbates the issue.
Innovation Solution
A method of fabricating a pixel structure involving a substrate with sub-pixel regions, an auxiliary electrode layer, insulating layers, and an organic light-emitting layer, where a laser process forms openings to connect the upper electrode layer with the auxiliary electrode layer, reducing the voltage drop effect by creating electrical connections through these openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal or transparent conductive oxide is used as the upper electrode of the organic light-emitting diode, then the device can be fabricated, but the resistance is higher than metal and the IR drop effect becomes more significant, resulting in poor brightness uniformity
Solution Approach 1:
The patent divides the electrode system into multiple components: a lower electrode, an auxiliary electrode, and an upper electrode. The auxiliary electrode is positioned between the lower and upper electrodes to create multiple electrical connection paths, segmenting the current flow to reduce the IR drop effect and improve brightness uniformity across the display.
Solution Approach 2:
The auxiliary electrode acts as an intermediary component between the lower electrode and the upper electrode. It provides additional electrical connection points that mediate the current distribution, reducing the voltage drop across the high-resistance transparent conductive oxide layer and improving overall brightness uniformity.
2Device complexity
If an electrode contact hole is formed outside of the display region to connect the upper electrode and electronic devices on the TFT array substrate, then the device structure can be completed, but the voltage drop (IR drop) effect results in brightness difference between central and peripheral pixel regions
Solution Approach 1:
The patent segments the electrode connection system by introducing auxiliary electrodes at multiple positions within the display region. This creates multiple parallel current paths from the lower electrode to the upper electrode, distributing the current flow and reducing the IR drop effect that causes brightness non-uniformity between central and peripheral regions.
Solution Approach 2:
The auxiliary electrodes are strategically positioned at specific locations (e.g., corners or edges) of the display region to provide localized electrical support. This creates non-uniform current distribution that compensates for the higher resistance paths, improving brightness uniformity across different regions of the display.
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 brightness uniformity across the display by reducing the voltage drop effect, thereby enhancing the overall display performance and addressing the issue of poor brightness uniformity in organic light-emitting displays.
Implementation Method 1
performing a laser process to form at least a third opening therein in the upper electrode layer and the organic light-emitting layer directly on the first opening
Implementation Method 2
such that the upper electrode layer and the auxiliary electrode layer are connected via welding through the third opening
Data Source
AI summary
A method of fabricating a pixel structure for an organic light-emitting display (OLED) is disclosed. A substrate having at least a sub-pixel region is provided. An auxiliary electrode layer and an insulating layer are formed on the substrate in the sub-pixel region, wherein the insulating layer has an opening to expose the auxiliary electrode layer. A lower electrode layer, an organic light emission layer, and an upper electrode layer are formed on the substrate, wherein the organic light emission layer fills the opening in the insulating layer. Another opening is formed in the upper electrode layer and the organic light emission layer directly on the opening in the insulating layer by performing a laser process, such that the upper electrode layer and the auxiliary electrode layer are welded together through the opening in the upper electrode layer and the organic light emission layer.