Transparent OLED Cathode Deposition via Segmented Masking
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Solution Overview
Problem
The challenge in manufacturing transparent organic light emitting display devices is the occurrence of position errors and shape deformation in the transmittance portion due to the deposition process of cathodes using fine metal masks, which affects the external light transmittance and image distortion.
Innovation Solution
The solution involves an organic light emitting display device structure with separate regions for light emission and transmittance, where a first electrode is patterned in an island form, covered by organic layers, and an auxiliary layer is used to facilitate the deposition of a second electrode without a fine metal mask, ensuring high transmittance and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine metal mask is used to pattern the cathode during deposition, then the cathode can be precisely formed in non-transmittance portions, but position errors and shape deformation occur in the transmittance portion
Solution Approach 1:
The substrate is divided into two distinct regions: a first region (non-transmittance) where the cathode is formed using a fine metal mask, and a second region (transmittance) where the cathode is not formed. This segmentation allows each region to be optimized independently - the first region achieves precise cathode patterning while the second region maintains high transmittance without position errors or shape deformation.
Solution Approach 2:
Different deposition conditions are applied to different regions of the substrate. In the first region, a fine metal mask is used to achieve precise cathode patterning. In the second region, no fine metal mask is used, allowing the cathode deposition to be skipped or modified, thereby eliminating position errors and shape deformation in the transmittance portion while maintaining overall device functionality.
2Manufacturing precision
If the cathode is formed in the transmittance portion using fine metal mask, then complete coverage is achieved, but external light transmittance is reduced and image distortion occurs
Solution Approach 1:
The substrate is divided into a first region where the cathode is fully formed for display functionality, and a second region where the cathode formation is omitted or modified to maintain high transmittance. This segmentation ensures that the transmittance portion achieves high external light transmission while the non-transmittance portion maintains complete cathode coverage for proper device operation.
Solution Approach 2:
The cathode structure is made non-uniform across the substrate: in the first region, a complete cathode layer is formed for light emission and display function, while in the second region, the cathode is either not formed or formed with reduced thickness, thereby achieving high transmittance without compromising the display functionality in the first region.
3Manufacturing precision
If fine metal mask is used for cathode deposition, then patterning is achieved, but manufacturing complexity and process difficulty increase
Solution Approach 1:
The manufacturing process is segmented into different steps for different regions. The fine metal mask is used only in the first region where precise patterning is required, while the second region uses a simplified process without the fine metal mask. This reduces overall manufacturing complexity compared to using the fine metal mask across the entire substrate.
Solution Approach 2:
Instead of using the fine metal mask to define where the cathode should NOT be formed (by blocking deposition), the approach is inverted: the fine metal mask is used only where the cathode SHOULD be formed, and the transmittance region is defined by the absence of the mask, allowing direct deposition or modified deposition processes that simplify manufacturing.
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 enhances external light transmittance and reduces image distortion, allowing for a more stable and efficient manufacturing process by eliminating the need for precise fine metal mask patterning, thereby improving the overall performance of the display device.
Implementation Method 1
an organic electroluminescent device (organic EL) is located
Implementation Method 2
there is an attempt to form a transmittance portion except for a region whereon a thin film transistor or an organic electroluminescent device (organic EL) is located
Data Source
AI summary
An organic light emitting display and a method of manufacturing the same. The organic light-emitting display is a transparent display where one can see through the display to view an image on the other side of the display. Each pixel of the display has a first region that includes an organic light emitting diode and a thin film transistor, and a larger second region that is transparent. The second region is made of either transparent layers or ultra-thin layers so that light is not blocked. A second electrode of the display may include magnesium and may be produced by a selective deposition process, so that use of a fine metal mask may be avoided.