OLED Subpixel Emissive Layer Stacking for Fabrication Simplification
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Solution Overview
Problem
Conventional RGB OLED display fabrication involves complex processes with high defect rates and costs due to the use of fine metal masks, and varying light emitting efficiencies and service lives of different color sub-pixels.
Innovation Solution
A display panel with a light emitting region comprising three sub-pixels: one for each primary color, where two sub-pixels share a vertically stacked emissive layer made of high-efficiency materials, and a color filter converts the combined light into the third color, reducing the number of mask processes and using materials with longer service life for filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RGB OLED fabrication uses fine metal masks for each sub-pixel, then each sub-pixel can emit its designated color, but the fabrication process becomes significantly more complicated with high defect rates and high costs
Solution Approach 1:
The patent merges the fabrication of multiple emissive layers into a single integrated process. Instead of separately depositing three different emissive layers for RGB sub-pixels using three different fine metal masks, the invention uses one fine metal mask to define all three sub-pixel regions, then sequentially forms different emissive layers across these regions. This consolidation reduces the number of masking operations from three to one, dramatically simplifying the fabrication process while maintaining color emission reliability.
Solution Approach 2:
The single fine metal mask serves multiple functions: it defines the patterns for red, green, and blue sub-pixels simultaneously, and serves as a universal template for subsequent emissive layer deposition. This multi-functional approach eliminates the need for separate masks for each color, reducing fabrication complexity and aligning with TRIZ principle of making one component perform multiple roles.
2Illumination intensity
If different light emitting materials are used for different color sub-pixels, then each sub-pixel emits its specific color, but the light emitting efficiency and service life vary greatly among sub-pixels
Solution Approach 1:
The patent applies local quality by assigning different emissive materials to different sub-pixel regions based on their specific color requirements. The red sub-pixel region receives red emissive material, green receives green emissive material, and blue receives blue emissive material, all within a single fabrication process. This localized material assignment ensures each sub-pixel emits its designated color while maintaining consistent fabrication conditions, thereby improving service life consistency.
3Reliability
If three separate emissive layers are fabricated using three different fine metal masks, then each sub-pixel achieves correct color emission, but the defect rate increases significantly
Solution Approach 1:
The patent merges three separate masking operations into a single masking operation. One fine metal mask defines all three sub-pixel patterns (red, green, blue) simultaneously, and subsequent emissive layer deposition is performed once across all regions. This eliminates the cumulative alignment errors and registration defects that would arise from three separate masking steps, dramatically reducing the overall defect rate while maintaining color emission accuracy.
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 simplifies the fabrication process, reduces defect rates and costs, and significantly improves light emitting efficiency and service life by using high-efficiency materials and longer-lasting color filters.
Implementation Method 1
a first sub-pixel for emitting light of a first color comprising a first emissive layer of a first light emitting material
Implementation Method 2
a second sub-pixel for emitting light of a second color comprising a second emissive layer of a second light emitting material
Implementation Method 3
a third sub-pixel comprising a third emissive layer comprising the first light emitting material and the second light emitting material in vertical stack
Implementation Method 4
a first color filter for converting light from the third sub-pixel into a third color
Data Source
AI summary
The present application discloses a display panel comprising a light emitting region comprising a plurality of light emitting units. Each of the plurality of light emitting units comprising a first sub-pixel comprising a first emissive layer of a first light emitting material for emitting light of a first color; a second sub-pixel comprising a second emissive layer of a second light emitting material for emitting light of a second color; and a third sub-pixel comprising a third emissive layer comprising the first light emitting material and the second light emitting material in vertical stack.