OLED Pixel Electrode Layout Without Shadow Mask Patterning
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Solution Overview
Problem
Conventional display devices face challenges in achieving high-definition displays with high aperture ratios and low power consumption, particularly due to limitations in the accuracy of metal mask evaporation methods which lead to deviations in pixel placement and dust-related defects.
Innovation Solution
The proposed solution involves a method for forming EL layers without a shadow mask, allowing for precise patterning of light-emitting elements of different colors, with a sacrificial layer and resist mask process that reduces the distance between EL layers and increases the aperture ratio, enabling higher resolution and reduced pixel size without the need for unique pixel arrangements like PenTile patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal mask evaporation method is used, then EL layers can be formed, but manufacturing precision deteriorates due to deviations in pixel placement and dust-related defects
Solution Approach 1:
The patent removes the shadow mask component entirely from the manufacturing process. Instead of using metal mask evaporation, the invention forms EL layers directly through sequential deposition of organic compounds between closely spaced electrodes, extracting the harmful masking step that causes dust contamination and placement deviations.
Solution Approach 2:
The patent segments the EL layer formation process into distinct sequential deposition steps for different organic compounds (hole injection layer, hole transport layer, emitting layer, electron transport layer, electron injection layer) between electrodes, allowing precise control of each layer without requiring a shadow mask.
2Area of stationary object
If conventional EL layer formation with shadow mask is used, then light-emitting elements can be patterned, but aperture ratio decreases due to larger distance between EL layers
Solution Approach 1:
The shadow mask is completely removed from the process. The patent achieves patterning through direct sequential deposition of organic compounds between electrodes spaced only 1-10 micrometers apart, eliminating the need for masking and enabling higher aperture ratios.
Solution Approach 2:
The patent transitions from a planar masking approach to a vertical deposition approach, where EL layers are formed by depositing materials from above between closely spaced electrodes in the vertical dimension, enabling precise patterning without masks and reducing the distance between EL layers.
3Productivity
If shadow mask method is used for patterning, then EL layers can be formed, but productivity decreases due to complex masking and cleaning steps
Solution Approach 1:
The patent removes the shadow mask and associated cleaning steps from the manufacturing process. EL layers are formed through direct sequential deposition between electrodes, eliminating multiple masking and cleaning operations and significantly improving manufacturing yield.
Solution Approach 2:
The patent performs preliminary electrode positioning and spacing (1-10 micrometers) before EL layer deposition, enabling direct patterning through sequential material deposition without requiring subsequent masking steps, thereby simplifying 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 approach results in a high-definition display device with a high aperture ratio, reduced power consumption, and improved manufacturing yield by eliminating the need for complex masking and cleaning steps, allowing for precise control over EL layer placement and minimizing defects.
Implementation Method 1
a first lower electrode, a first EL layer over the first lower electrode, a second lower electrode, a second EL layer over the second lower electrode, and an upper electrode over the first EL layer and the second EL layer
Implementation Method 2
By voltage application to this element, the light-emitting organic compound can emit light
Data Source
AI summary
A display device with high display quality is provided. The display device includes a first lower electrode, a first EL layer over the first lower electrode, a second lower electrode, a second EL layer over the second lower electrode, an upper electrode over the first EL layer and the second EL layer, a first region not provided with the first lower electrode below the first EL layer, and a second region not provided with the second lower electrode below the second EL layer. In the first region, the upper electrode is positioned not to be in contact with the first lower electrode. In the second region, the upper electrode is positioned not to be in contact with the second lower electrode.