Multi-Layer Bank Structure for OLED Encapsulation Integrity
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Solution Overview
Problem
Display apparatuses face issues with local defects in the encapsulation layer leading to impurity infiltration paths, which can propagate to neighboring pixels, compromising the integrity and performance of the OLED pixels.
Innovation Solution
The display apparatus incorporates a multi-layered bank structure comprising inorganic and metal bank layers with protruding tips, an intermediate layer, and an inorganic encapsulation layer that directly contacts the tips, along with a planarization layer and protection layer, to prevent impurity infiltration and enhance encapsulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional encapsulation layer is used to seal the light-emitting diode, then the basic protection against oxygen and moisture is provided, but local defects in the encapsulation layer create impurity infiltration paths that propagate to neighboring pixels
Solution Approach 1:
The encapsulation structure is divided into multiple independent bank layers (first inorganic bank layer, first metal bank layer, second inorganic bank layer, second metal bank layer) with each layer providing a separate barrier. The bank layer is segmented into multiple sub-layers that can be independently formed and controlled, creating redundant protection paths that prevent defect propagation between pixels.
Solution Approach 2:
The encapsulation structure combines different materials with complementary properties: inorganic materials (silicon oxide, silicon nitride) provide chemical stability and barrier properties, while metal layers (aluminum, titanium) provide both barrier function and mechanical strength. This composite approach creates a multi-functional encapsulation system that addresses both protection and structural requirements.
2Reliability
If the encapsulation layer is made thicker to prevent defects, then protection is improved, but the device thickness and weight increase, limiting application scope
Solution Approach 1:
Instead of using a single thick encapsulation layer, the protection function is segmented into multiple thin layers. Each bank layer is formed as a separate thin film (typically nanometer to micrometer scale), and the cumulative protection equivalent to a thick single layer is achieved through the stacked configuration of multiple layers, each contributing to the overall barrier performance.
Solution Approach 2:
The encapsulation protection is extended from a single-dimensional thick layer to a multi-dimensional stacked structure. The bank layers are arranged in vertical stacks (first inorganic, first metal, second inorganic, second metal) creating a three-dimensional encapsulation architecture that provides enhanced protection while maintaining minimal thickness in the horizontal plane.
3Ease of manufacture
If a simple encapsulation structure is used to reduce manufacturing complexity, then ease of manufacture is improved, but local defects can still propagate to neighboring pixels
Solution Approach 1:
The manufacturing process is segmented into sequential deposition steps for each bank layer, allowing standard thin-film deposition techniques to be used repeatedly. Each layer can be formed using conventional equipment and processes, making the complex multi-layer structure manufacturable with existing technology while achieving superior defect isolation.
Solution Approach 2:
The bank layer structure serves multiple functions simultaneously: it provides encapsulation protection, acts as a barrier to impurity infiltration, provides mechanical support, and enables defect isolation between pixels. This multi-functionality is achieved through a unified manufacturing approach that deposits layered structures serving all these purposes in a single manufacturing sequence.
Data Source
AI summary
A display apparatus includes a pixel electrode, a bank layer including a first inorganic bank layer, a first metal bank layer, a second inorganic bank layer, and a second metal bank layer, which are sequentially stacked, and in which a pixel opening overlapping the pixel electrode and penetrating the first inorganic bank layer, the first metal bank layer, the second inorganic bank layer, and the second metal bank layer is defined, an intermediate layer disposed on the pixel electrode through the pixel opening of the bank layer, a counter electrode disposed on the intermediate layer through the pixel opening of the bank layer, and an inorganic encapsulation layer on the counter electrode. The counter electrode directly contacts with a side surface of the first metal bank layer defining the pixel opening.