Protective Layer for OLED Cathode Patterning
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Solution Overview
Problem
The organic light emitting device described in Patent Document 1 faces reliability issues due to damage and deterioration of the organic light emitting layer during the patterning process of the electrodes, leading to a decrease in device reliability.
Innovation Solution
A display device configuration with light emitting elements having an anode electrode, an organic light emitting layer, and a first cathode electrode separated for each sub-pixel, covered by a protective layer, and a second cathode electrode connected to the first cathode electrodes, which helps in preventing exposure to process gases and chemicals, thereby enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first upper electrode and second upper electrode are directly stacked without a protective layer, then the device complexity is reduced, but the organic light emitting layer is exposed to process gas and chemical liquid during patterning, causing damage and deterioration
Solution Approach 1:
A protective layer is introduced as an intermediary component between the organic light emitting layer and the upper electrodes. This protective layer serves as a barrier that prevents process gas and chemical liquid from reaching and damaging the organic light emitting layer during patterning processes, while still allowing the device to function properly.
Solution Approach 2:
The protective layer is formed in advance before the patterning process of the upper electrodes. This pre-formed protective layer acts as a cushion or shield that protects the organic light emitting layer from potential damage during subsequent manufacturing steps, ensuring the layer's integrity is maintained throughout the fabrication process.
2Ease of manufacture
If the organic light emitting layer is exposed to process gas and chemical liquid during patterning, then the electrode patterning can be completed, but the organic light emitting layer is damaged and deteriorated
Solution Approach 1:
The protective layer acts as an intermediary that allows the patterning process to proceed normally while preventing the harmful effects of process gas and chemical liquid from reaching the organic light emitting layer. This enables manufacturers to complete electrode patterning without compromising the integrity of the organic light emitting layer.
3Manufacturing precision
If the first cathode electrode is separated for each sub-pixel, then the color mixing between sub-pixels is reduced, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The second cathode electrode is designed as a unified structure that connects to multiple first cathode electrodes simultaneously. This merging approach allows the manufacturing process to complete the cathode electrode formation in fewer steps compared to creating entirely separate cathode structures for each sub-pixel, thereby improving manufacturing efficiency while still maintaining color separation through the underlying first cathode electrode segmentation.
Data Source
AI summary
A display device includes an anode electrode, an organic light emitting layer, and a first cathode electrode. Provided are a plurality of light emitting elements in which the anode electrode, the organic light emitting layer, and the first cathode are separated for each sub-pixel, a protective layer covering the plurality of light emitting elements, and a second cathode electrode provided on the protective layer. The second cathode electrode is connected to each separated first cathode electrode.