Tapered Structure Layer for Organic EL Display Maskless Deposition
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Solution Overview
Problem
The high manufacturing cost of organic EL display devices due to the need for accurate and expensive vapor deposition masks, which require frequent cleaning and replacement, increases the number of man-hours and production costs.
Innovation Solution
The use of a tapered structure layer with overhanging side surfaces to form contact holes for connecting the upper electrode to a wire outside the display area, allowing for the deposition of the organic layer and upper electrode without a vapor deposition mask, and the formation of an island-shaped portion covered by the upper electrode, reducing the need for complex and costly masking processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a vapor deposition mask is used to prevent organic layer deposition outside the display area, then the organic layer can be precisely deposited only in the display area, but the manufacturing cost increases due to the need for highly accurate processing, expensive masks, regular cleaning and replacement, and increased man-hours
Solution Approach 1:
The patent divides the deposition process into two distinct stages: (1) depositing the organic layer over the entire substrate including outside the display area, and (2) subsequently forming a mask layer that selectively removes the organic layer outside the display area. This segmentation eliminates the need for precise mask alignment during deposition, reducing manufacturing complexity while maintaining deposition precision.
Solution Approach 2:
The patent performs the organic layer deposition over the entire substrate before forming the mask layer. This preliminary action allows the organic layer to be deposited without any mask, avoiding the need for expensive and complex vapor deposition masks. The mask layer is then formed and patterned to define the display area, selectively removing organic material outside the display region.
2Manufacturing precision
If a vapor deposition mask is used to protect the organic layer from being vapor-deposited outside the display area, then the organic layer remains intact only in the display area, but the number of man-hours and manufacturing cost increase due to frequent cleaning and replacement of masks
Solution Approach 1:
The mask layer is formed from the same organic material as the organic layer itself, allowing it to be processed using the same deposition techniques without requiring separate mask materials. The mask layer automatically forms a protective structure that defines the display area, eliminating the need for external vapor deposition masks and their associated maintenance activities.
3Manufacturing precision
If a vapor deposition mask is used to prevent organic layer deposition outside the display area, then the organic layer is precisely formed in the display area, but the device complexity increases due to the need for expensive and complex masking equipment and processes
Solution Approach 1:
Instead of using a mask to prevent organic layer deposition in certain areas during the deposition process, the patent inverts the approach by depositing the organic layer everywhere first, then using a mask layer to remove the material where it should not be present. This inversion eliminates the need for complex vapor deposition mask systems while achieving the same boundary definition precision.
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 method simplifies the manufacturing process, reduces the number of times a vapor deposition mask is needed, and lowers production costs by enabling the deposition of organic layers and electrodes without a mask, while maintaining the integrity of the organic EL display device.
Implementation Method 1
a vapor deposition step or the like using a vapor deposition mask is performed in a manufacturing step so as to prevent the organic layer, which is deposited before the upper electrode, from being vapor-deposited outside the display area
Data Source
AI summary
An organic EL display device includes: a lower electrode disposed in each of pixels; an upper electrode disposed so as to cover the whole of the display area; an organic layer disposed between the lower electrode and the upper electrode and composed of a plurality of layers including a light-emitting layer composed of an organic material; a wire formed outside the display area and composed of conductive material; and a tapered structure layer formed on the wire and including tapered portions at each of which a side surface portion not in contact with the wire extends so as to overhang the wire. At least one layer of the organic layer is formed on the tapered structure layer. The tapered structure layer forms a contact hole surrounded by the side surface portions. The upper electrode is in contact with the wire through the contact hole.