OLED Cathode Contact via Black Matrix Extension
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Solution Overview
Problem
Conventional active matrix organic light-emitting diode (AM-OLED) devices face issues with cathode breakage or collapse due to poor step coverage, affecting the quality and reliability of the device, and the complexity of forming extra cathode contacts increases manufacturing complexity and reduces aperture ratio.
Innovation Solution
The implementation of a top cathode contact system using a color filter substrate with a black matrix layer extending to the peripheral region, where conductive components connect the black matrix layer to the cathode, eliminating the need for cathode contacts on the lower substrate and improving electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cathode contacts are formed on the lower substrate to improve electrical connection, then electrical connection between control circuit and cathode is improved, but the contact area between cathode and cathode contact breaks easily due to bad step coverage
Solution Approach 1:
The patent inverts the conventional cathode contact structure by moving the cathode contact from the lower substrate to the upper substrate. This inversion eliminates the step coverage problem at the cathode contact opening on the lower substrate, as the cathode is now contacted from above where there is no underlying structure causing poor adhesion. The cathode contact on the upper substrate directly contacts the cathode layer without encountering the step coverage issue that plagues lower substrate contacts.
Solution Approach 2:
The patent transitions the cathode contact location from the horizontal plane (lower substrate) to the vertical dimension (upper substrate). By placing the cathode contact on the upper substrate, the design moves the contact point to a different spatial dimension where the cathode layer is more accessible and can form a robust contact area without the constraints of the lower substrate's topography.
2Reliability
If extra cathode contacts are formed to improve electrical connection, then electrical connection between control circuit and cathode is improved, but the complexity of manufacturing process increases and aperture ratio is reduced
Solution Approach 1:
The patent merges the cathode contact function with the existing upper substrate structure. The upper substrate, which already exists for the display function, is extended or modified to include the cathode contact functionality. This integration eliminates the need for separate cathode contact structures on the lower substrate, thereby simplifying the manufacturing process and maintaining the aperture ratio without compromising electrical connection reliability.
Solution Approach 2:
The upper substrate serves multiple functions: it provides the display surface and simultaneously houses the cathode contact structure. This multi-functionality eliminates the need for dedicated cathode contact elements on the lower substrate, reducing manufacturing complexity and preserving aperture ratio while ensuring reliable electrical connection between the control circuit and cathode.
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 solution prevents cathode breakage and collapse, enhances the reliability and quality of the AM-OLED device by improving electrical connections and simplifying the manufacturing process while maintaining the aperture ratio.
Implementation Method 1
A bias voltage may be applied between the anode and the cathode to activate the organic electroluminescent layer to emit light for image display
Data Source
AI summary
An organic light emitting display device is disclosed, which including an active matrix substrate with an array of active elements disposed in an active region and a control circuit disposed in a peripheral region. A color filter substrate is oppositely disposed to the active matrix substrate, including color filter elements with different colors enclosed by a black matrix layer in a region corresponding to the active region and an extension of the black matrix layer in a region corresponding to the peripheral region. An array of OLED pixel is interposed between the active matrix substrate and the color filter substrate on the active region. Each of the OLED pixels includes an anode, an organic electroluminescent layer, and a cathode. A first conductive component electrically connects the control circuit and the extension of the black matrix layer. A second conductive component electrically connects the black matrix layer and the cathode.