OLED Dual Bank Layer Reduces Width and Prevents Color Mixing
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Solution Overview
Problem
The degradation of display quality in organic light emitting diode (OLED) display devices due to color-mixed emitting layers formed through a soluble process, which limits the resolution and increases the bank width of the bank layer, preventing the reduction of sub-pixel size and the increase in the number of pixels per unit area.
Innovation Solution
The implementation of a dual bank layer system where sub-pixels of the same color are grouped together with a first bank layer dividing adjacent sub-pixels and a second bank layer dividing sub-pixel groups, allowing for a reduction in the bank width while preventing color mixing, and using hydrophilic and hydrophobic materials to manage the emitting material solutions effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single bank layer is used to divide sub-pixels during the soluble process, then the sub-pixels can be separated, but the bank width must be increased to prevent color mixing of emitting material solutions
Solution Approach 1:
The patent divides the single bank layer into two separate bank layers: a first bank layer that divides adjacent sub-pixels and a second bank layer that divides sub-pixel groups. This segmentation allows each bank layer to have a reduced width while collectively preventing color mixing, thus resolving the contradiction between preventing color mixing and reducing bank width.
Solution Approach 2:
The patent introduces a vertical dimension by stacking two bank layers at different heights. The first bank layer is formed at a lower level and the second bank layer is formed at a higher level, creating a three-dimensional structure. This dimensional change allows the bank width to be reduced while maintaining the color separation function through the combined effect of both layers.
2Manufacturing precision
If the bank width is increased to prevent color mixing, then color separation is improved, but the sub-pixel size cannot be reduced and the number of pixels per unit area cannot be increased
Solution Approach 1:
By segmenting the color separation function into two bank layers, each layer can be narrower. The first bank layer handles separation between adjacent sub-pixels while the second bank layer handles separation between sub-pixel groups. This segmentation enables sub-pixel size reduction and increases the number of pixels per unit area while maintaining effective color separation.
Solution Approach 2:
The vertical stacking of two bank layers creates a three-dimensional color separation system. This allows the horizontal bank width to be reduced, enabling smaller sub-pixels and higher pixel density, while the vertical arrangement of the two layers maintains the color separation function.
3Device complexity
If a single bank layer is used, then the structure is simple, but the resolution is limited due to the increased bank width
Solution Approach 1:
The patent segments the bank layer structure into two functional layers with different responsibilities. The first bank layer divides adjacent sub-pixels and the second bank layer divides sub-pixel groups. This segmentation enables higher resolution by allowing narrower individual layers while maintaining the overall separation function, accepting increased structural complexity as a trade-off for improved resolution.
Solution Approach 2:
By transitioning from a single two-dimensional bank layer to a three-dimensional stacked structure of two layers, the patent achieves higher resolution. The vertical arrangement allows each layer to be narrower, enabling more pixels per unit area, while the combined structure maintains the color separation function.
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 prevents color mixing, improves the uniformity of the emitting layer thickness, and allows for a higher resolution by reducing the sub-pixel size and increasing the number of pixels per unit area, while maintaining the display quality.
Implementation Method 1
Since the bank layer 73 confines the red, green and blue emitting material solutions 12a and 12b having a water solubility, the bank layer 73 may be formed of a hydrophobic material or a top surface of the bank layer 73 may have a hydrophobicity through a surface treatment.
Implementation Method 2
The first bank layer may be formed of a hydrophilic material and the second bank layer may be formed of a hydrophobic material
Data Source
AI summary
An organic light emitting diode display device (100) including: a plurality of pixels (101, 102, 103) each including first (101a, 102a, 103a), second (101b, 102b, 103b) and third sub-pixels (101c, 102c, 103c), wherein the first sub-pixels (101a, 102a, 103a) of adjacent pixels (101, 102, 103), the second sub-pixels (101b, 102b, 103b) of adjacent pixels (101, 102, 103) and the third sub-pixels (101c, 102c, 103c) of adjacent pixels (101, 102, 103) constitute a plurality of sub-pixel groups (150); a first bank layer (171) dividing the plurality of sub-pixel groups (150) and dividing the first (101a, 102a, 103a), second (101b, 102b, 103b) and third sub-pixels (101c, 102c, 103c); and a second bank layer (173) on the first bank layer (171), the second bank layer (173) dividing the first (101a, 102a, 103a), second (101b, 102b, 103b) and third sub-pixels (101c, 102c, 103c).