Organic EL Display Electrode Segmentation for Brightness
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Solution Overview
Problem
In organic electroluminescent (EL) display devices with top-emission structures, the high resistivity of transparent electrode materials leads to insufficient voltage supply at the cathode wiring, resulting in decreased brightness due to the need for auxiliary electrodes that complicate production and reduce effective pixel area.
Innovation Solution
The solution involves forming lower electrodes in stripes on a substrate, an insulating layer, auxiliary electrodes for the upper electrodes connected at the broadest width of broadened insulating barrier walls, and upper transparent electrodes using a sputtering method, ensuring efficient voltage distribution and high opening ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent electrode material such as ITO is used for upper electrode, then transparency is maintained, but voltage supply becomes insufficient due to high resistivity
Solution Approach 1:
The upper electrode system is segmented into two parts: a transparent electrode (ITO) for light emission and an auxiliary electrode (low-resistivity metal) for voltage supply. This segmentation allows each component to fulfill its specific function - the transparent electrode maintains optical properties while the auxiliary electrode ensures electrical reliability.
Solution Approach 2:
The auxiliary electrode acts as an intermediary between the power supply and the transparent electrode. It provides a low-resistivity path for current flow and connects to the transparent electrode through connection portions, mediating the electrical connection without compromising the transparency of the main electrode.
2Reliability
If auxiliary electrode is formed to protrude toward inside of emitting region, then voltage supply is improved, but effective pixel region becomes smaller
Solution Approach 1:
The auxiliary electrode is positioned in a different spatial dimension - it is formed on the insulating layer beneath the organic EL layer, rather than protruding into the emitting region from the top. This dimensional arrangement allows voltage supply improvement without reducing the effective pixel area.
Solution Approach 2:
The auxiliary electrode and connection portions are formed in advance during the manufacturing process, before the organic EL layer is deposited. This preliminary action ensures proper electrical connection is established without requiring post-processing modifications that would reduce pixel area.
3Ease of manufacture
If auxiliary electrode protrudes into emitting region, then connection is achieved, but production process becomes more complex
Solution Approach 1:
The formation of the auxiliary electrode and connection portions is merged into a single manufacturing step. Both are deposited simultaneously as part of the same film formation process, eliminating the need for separate processing steps and reducing overall production complexity.
Solution Approach 2:
The auxiliary electrode structure serves multiple functions: it provides voltage supply, forms electrical connections, and defines pixel boundaries. This multi-functionality reduces the need for additional dedicated components and simplifies the overall manufacturing process.
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 enhances the brightness and fineness of displayed images by maintaining high voltage levels and simplifying the production process while maintaining a high opening ratio, allowing for efficient and easy image display.
Implementation Method 1
upper transparent electrodes arranged in stripes in a direction intersecting with the lower electrodes
Data Source
AI summary
An organic electroluminescent display device includes a substrate, lower electrodes arranged in stripes on the substrate, an insulating layer arranged on the lower electrodes, upper transparent electrodes arranged in stripes in a direction intersecting with the lower electrodes, an organic electroluminescent layer arranged between the lower electrodes and the upper transparent electrodes, electrodes auxiliary to the upper electrodes arranged on the insulating layer and connected with the upper transparent electrodes, and insulating barrier walls arranged on the insulating layer or the electrodes auxiliary to the upper electrodes, the widths of which are broadened in the upper portions, wherein the upper electrodes are connected to the electrodes auxiliary to the upper electrodes at a position between the insulating layer and a region where the width of the insulating barrier wall is broadest, and are connected within a region corresponding to the broadest width of the insulating barrier wall; and a method for producing the device.