OLED Pixel Electrode Capacitor Structure for Aperture Ratio
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Solution Overview
Problem
The enlargement of capacitors in active matrix organic light-emitting displays to increase charging capacity leads to a decrease in the aperture ratio and brightness, as it reduces the light-emitting area of the OLED.
Innovation Solution
The design incorporates a pixel electrode and a rear electrode, both acting as translucent electrodes with a silver alloy layer between indium tin oxide (ITO) layers, functioning as a capacitor, and a method of manufacturing that forms these electrodes on the same layer as the gate electrode and source/drain electrodes, allowing for a structure that maintains a sufficient aperture ratio without additional capacitor space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacitor is enlarged to increase charging capacity, then the charging capacity is improved, but the aperture ratio and brightness decrease
Solution Approach 1:
The patent combines the capacitor structure with the pixel electrode structure by forming the capacitor electrode and pixel electrode in the same process step and on the same substrate region. This merging allows the capacitor to share space with the pixel electrode, eliminating the need for separate capacitor area and preventing aperture ratio reduction while maintaining sufficient charging capacity.
Solution Approach 2:
The pixel electrode structure is given dual functionality: it serves both as the light-emitting pixel electrode and as one of the capacitor electrodes. This multi-functionality allows the same structural region to fulfill both display and storage functions, resolving the contradiction between aperture ratio and charging capacity.
2Quantity of substance
If the capacitor is enlarged to increase charging capacity, then the charging capacity is improved, but the brightness decreases
Solution Approach 1:
By merging the capacitor electrode formation with the pixel electrode formation process, the patent ensures that the light-emitting area is not reduced. The capacitor functionality is integrated into the existing pixel electrode structure, maintaining brightness while providing sufficient charging capacity through the combined structure.
3Quantity of substance
If additional capacitor space is allocated, then the charging capacity is improved, but the device complexity increases
Solution Approach 1:
The patent merges the capacitor electrode and pixel electrode into a single integrated structure formed in the same process step. This consolidation reduces device complexity by eliminating separate capacitor structures and simplifying the manufacturing process, while still providing adequate charging capacity through the unified electrode design.
Solution Approach 2:
The unified electrode structure performs multiple functions simultaneously - serving as both the pixel electrode for light emission and the capacitor electrode for charge storage. This multi-functionality reduces the overall number of components needed, thereby decreasing device complexity while maintaining charging capacity.
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 aperture ratio, enabling high-resolution image display with stable brightness by utilizing the pixel electrode and rear electrode as a capacitor, eliminating the need for additional capacitor space and leveraging constructive interference for stronger light emission.
Implementation Method 1
The OLED emits light and forms a desired image by receiving an appropriate driving signal from the TFT and the capacitor
Implementation Method 2
leveraging constructive interference for stronger light emission
Data Source
AI summary
An organic light-emitting display having an improved aperture ratio, the organic light-emitting display including a rear electrode, an opposite electrode, and a pixel electrode between the rear electrode and the opposite electrode. Here, an insulating layer is interposed between the pixel electrode and the rear electrode, wherein the pixel electrode, the insulating layer, and the rear electrode are configured as a capacitor of the organic light-emitting display. In such a structure, as the capacitor is disposed in a light-emitting area where the pixel electrode exists, it is not necessary to provide an additional space for a capacitor, thus improving an aperture ratio of the display.