Mesh Auxiliary Electrode for OLED IR Drop Reduction
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Solution Overview
Problem
Conventional top emission organic light emitting displays experience significant IR drop in the cathode electrode due to high resistance materials like ITO and MgAg, leading to non-uniform image quality and display characteristics, especially as display panel sizes increase.
Innovation Solution
An organic light emitting display design featuring a mesh-type auxiliary electrode with lower specific resistance, positioned on an upper substrate and electrically connected to the cathode electrode via a transparent conductive layer, which reduces or prevents IR drop by distributing the electrical load across non-emission regions between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive material such as ITO or MgAg is used for the cathode electrode to enable light emission, then light transparency is improved, but resistance increases causing high IR drop
Solution Approach 1:
The cathode electrode system is segmented into two parts: the original transparent cathode electrode and a newly introduced auxiliary electrode. The auxiliary electrode is positioned at non-emission regions (such as the black matrix area) and electrically connected to the cathode electrode, forming a segmented structure that distributes current flow paths and reduces overall resistance without affecting light emission regions.
Solution Approach 2:
The auxiliary electrode acts as an intermediary element that mediates between the power supply and the transparent cathode electrode. By providing an additional electrical connection path through the black matrix region, it reduces the effective resistance of the cathode electrode system while maintaining the transparency requirement for light emission areas.
2Area of stationary object
If the display panel size is increased to improve display area, then aperture ratio is improved, but IR drop in the cathode electrode is greatly increased
Solution Approach 1:
The auxiliary electrode is divided into multiple segments corresponding to different pixel regions, with each segment electrically connected to the cathode electrode in its respective area. This segmented configuration allows the resistance reduction effect to be distributed across the entire large display panel, effectively managing IR drop in larger display areas.
Solution Approach 2:
The auxiliary electrode utilizes the black matrix region, which is traditionally a non-functional area, to create an additional dimensional pathway for current flow. This effectively adds a parallel electrical path in the spatial dimension, reducing resistance without occupying additional display area.
3Illumination intensity
If the cathode electrode is made thinner to improve transparency, then light transmission is improved, but resistance increases
Solution Approach 1:
The electrical conduction function is segmented between the thin transparent cathode electrode (optimized for light transmission) and the auxiliary electrode (optimized for electrical conduction). This segmentation allows the cathode electrode to be made thinner for better transparency while the auxiliary electrode compensates for the increased resistance.
Solution Approach 2:
Different regions of the electrode system have different functional qualities: the cathode electrode in emission regions has optimized transparency for light transmission, while the auxiliary electrode in non-emission regions provides enhanced electrical conduction. This local quality differentiation resolves the contradiction between thickness and resistance.
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 auxiliary electrode effectively reduces IR drop in the cathode electrode, enhancing the uniformity of image quality and display characteristics by lowering the resistance and improving the aperture ratio, even in larger display sizes.
Implementation Method 1
the mesh-type auxiliary electrode corresponding to non-emission regions between the pixels and electrically connected to the cathode electrode
Implementation Method 2
IR drop (i.e., voltage drop) in a cathode electrode is prevented or reduced
Data Source
AI summary
An organic light emitting display is capable of reducing or preventing IR drop in a cathode electrode. An organic light emitting display includes a first substrate and a second substrate. The first substrate has a plurality of pixels located thereon, each of the pixels comprising an organic light emitting diode, wherein a cathode electrode of the organic light emitting diode including a transparent material is located on substantially an entire area of the pixels. The second substrate has a mesh type auxiliary electrode located thereon at a side facing the pixels, the mesh-type auxiliary electrode corresponding to non-emission regions between the pixels and electrically connected to the cathode electrode.