Top Electrode Connection Structure for Uniform OLED Emission
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Solution Overview
Problem
The manufacturing of large-sized and high-definition electroluminescent display devices faces challenges due to the high costs and variations associated with the vacuum thermal evaporation process, particularly in forming light-emitting layers, which results in issues like sagging and shadow effects from fine metal masks.
Innovation Solution
The electroluminescent display device incorporates a substrate with a first electrode, a connection pattern, a bank, a light-emitting layer, and an auxiliary pattern, where the light-emitting layer includes charge auxiliary layers and the auxiliary pattern has a greater inclination angle than the bank, reducing contact resistance and enabling uniform emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum thermal evaporation process with fine metal mask is used to form light-emitting layers, then manufacturing precision of light-emitting layers is improved, but manufacturing cost increases and manufacturing variations occur due to mask preparation, sagging, and shadow effects
Solution Approach 1:
The patent removes the fine metal mask from the manufacturing process entirely. Instead of using mask-based evaporation, the light-emitting layers are formed through a maskless deposition process where the bank structures serve as natural masks, eliminating mask preparation costs and associated manufacturing variations while maintaining pattern definition accuracy
Solution Approach 2:
The bank structures serve multiple functions: they define the pixel boundaries, act as side walls for material deposition, and serve as the masking structure itself. This multi-functionality eliminates the need for separate fine metal masks while maintaining manufacturing precision
2Manufacturing precision
If vacuum thermal evaporation process is used for large-sized displays, then light-emitting layers can be formed, but manufacturing variations and shadow effects increase due to mask sagging and large area coverage challenges
Solution Approach 1:
The patent divides the large display area into multiple pixel regions defined by bank structures. Each pixel region is independently formed with its own light-emitting layer, allowing localized control and eliminating shadow effects that occur in large-area mask evaporation. The segmented approach enables uniform material deposition across the entire large display area
Solution Approach 2:
The bank structures serve as intermediary elements that guide material deposition and define emission regions. These physical structures mediate between the deposition source and substrate, ensuring uniform light-emitting layer formation across large areas without mask-related shadow effects
Data Source
AI summary
An electroluminescent display device includes a substrate, a first electrode on the substrate, a connection pattern on the substrate and formed of a same material as the first electrode, a bank covering edges of the first electrode and the connection pattern, a light-emitting layer on the first electrode, a second electrode on the light-emitting layer, the bank, and the connection pattern, and an auxiliary pattern between the second electrode and the connection pattern, wherein a side surface of the auxiliary pattern has a greater inclination angle than a side surface of the bank.