OLED Auxiliary Electrode Layer Design for Cathode Resistance
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Solution Overview
Problem
Top-emission OLED display panels face challenges with high sheet resistance in metal cathodes, requiring more power for operation and potential damage to the organic layer during indium tin oxide deposition, and defects from auxiliary electrode formation processes.
Innovation Solution
An organic light emitting diode display panel with a novel structure featuring a base substrate, first and second electrode layers, and an auxiliary electrode layer in the inter-subpixel region, where the auxiliary electrode layer is thicker and has an inverted trapezoidal shape, reducing cathode resistance and avoiding damage to the organic layer during deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker cathode layer is used to reduce sheet resistance, then electrical conductivity is improved, but the organic layer may be damaged during deposition
Solution Approach 1:
The electrode structure is segmented into three distinct layers: a reflective anode, a thin transparent cathode, and a thick auxiliary electrode. This segmentation allows each layer to perform its specific function - the thin cathode maintains optical transparency and avoids organic layer damage, while the thick auxiliary electrode provides the necessary electrical conductivity and low sheet resistance.
Solution Approach 2:
Different regions of the electrode structure have different thicknesses and properties. The cathode layer is thin in the emission region to maintain transparency, while the auxiliary electrode is thick in the inter-subpixel region to provide electrical connection. This local variation in quality optimizes both optical and electrical performance.
2Illumination intensity
If a transparent cathode material like indium tin oxide is used, then optical transparency is improved, but sheet resistance increases requiring more power
Solution Approach 1:
The electrode system uses a composite structure combining a transparent conductive oxide (TCO) cathode with a metal auxiliary electrode. The TCO provides optical transparency, while the metal auxiliary electrode contributes low resistance and high conductivity. Together, they achieve both transparency and low power consumption that neither material could provide alone.
3Reliability
If auxiliary electrodes are formed in the same layer as the cathode, then electrical connectivity is improved, but manufacturing defects increase
Solution Approach 1:
The auxiliary electrode is formed before the organic light-emitting layer is deposited. This preliminary action ensures that the auxiliary electrode is already in place to provide electrical connection, while subsequent processing steps can focus on forming the organic layer without risking damage from repeated deposition cycles.
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 reduces cathode resistance, enhances display quality, and extends the lifetime of the OLED panel by ensuring electrical connectivity and minimizing defects, while allowing for a thicker cathode layer without compromising optical transparency.
Implementation Method 1
the auxiliary electrode layer and the second electrode layer are in contact with each other; and the auxiliary electrode layer has a thickness larger than that of a first portion of the second electrode layer
Implementation Method 2
a light emitting layer in the subpixel region on a side of the first electrode layer distal to the base substrate
Data Source
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AI summary
An organic light emitting diode display panel, a display apparatus having the same, and a fabricating method thereof. The organic light emitting diode display panel has a plurality of pixels, each of which includes a subpixel region(SR) and an inter-subpixel region(ISR). The organic light emitting diode display panel includes a base substrate(1), a first electrode layer(2) on the base substrate(1),a light emitting layer(3a) in the subpixel region(SR) on a side of the first electrode layer(2) distal to the base substrate(1),a second electrode layer(4) on a side of the light emitting layer(3a) distal to the first electrode layer(2),and an auxiliary electrode layer(5) in the inter-subpixel region(ISR) in a same layer as the second electrode layer(4). The auxiliary electrode layer(5) and the second electrode layer(4) are in contact with each other. The auxiliary electrode layer(5) has a thickness larger than that of the second electrode layer(4).