OLED Sub-Pixel Resonator Layout for Uniform Reflective Layer Height
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Solution Overview
Problem
The complexity of the uneven shape of the semi-transmissive reflective layer in organic electroluminescence display devices increases the number of processing steps, leading to decreased productivity.
Innovation Solution
A display device with sub-pixels configured to have the same height for their semi-transmissive reflective layers, utilizing a resonator structure between a first electrode and the semi-transmissive reflective layer to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the film thickness of the protective layer is changed for each emission color, then the light extraction efficiency is improved, but the uneven shape of the surface becomes complicated and the number of processing steps increases
Solution Approach 1:
The patent applies local quality by providing the optical adjustment layer only in specific regions (first and third sub-pixels) rather than uniformly across all sub-pixels. This localized approach allows different film thicknesses for different emission colors where needed, while maintaining a simple surface profile in other regions, thus improving light extraction efficiency without complicating the overall surface shape.
Solution Approach 2:
The patent segments the display into different types of sub-pixels (first, second, and third sub-pixels) with different configurations. The first and third sub-pixels include the optical adjustment layer with specific film thicknesses, while the second sub-pixel does not. This segmentation allows each region to be optimized for its specific emission characteristics without affecting the entire surface complexity.
2Reliability
If the film thickness of the protective layer is changed for each emission color, then the light extraction efficiency is improved, but the number of processing steps increases and productivity decreases
Solution Approach 1:
By localizing the optical adjustment layer to specific sub-pixel regions rather than applying different thicknesses across the entire surface, the number of processing steps is reduced. The manufacturing process can use a single deposition step with spatially selective formation, improving productivity while still achieving the light extraction efficiency benefits in the regions where it is most needed.
3Productivity
If the heights of the semi-transmissive reflective layers are made the same, then the surface shape is simplified and productivity is improved, but the light extraction efficiency may be compromised
Solution Approach 1:
The patent resolves this contradiction by applying the optical adjustment layer locally in the first and third sub-pixels where light extraction enhancement is most beneficial, while keeping the semi-transmissive reflective layer height uniform across all sub-pixels. This localized approach maintains a simple overall surface profile for high productivity while still achieving improved light extraction efficiency in the specific regions where the optical adjustment layer is present.
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 configuration simplifies the surface shape of the semi-transmissive reflective layer, reducing processing complexity and enhancing light extraction efficiency while maintaining high productivity.
Implementation Method 1
a resonator structure is configured by the first electrode and the semi-transmissive reflective layer
Data Source
AI summary
Display devices that suppress complications due to uneven shape of a surface on which a semi-transmissive reflective layer is formed are disclosed. In one example, a display device includes first sub-pixels, second sub-pixels, and third sub-pixels. The first sub-pixel includes a first light emitting element that emits first light and third light, the second sub-pixel includes a second light emitting element that emits second light, and the third sub-pixel includes a third light emitting element that emits first light and third light. The light emitting elements respectively include a first electrode, an organic layer including a light emitting layer, a second electrode, and a semi-transmissive reflective layer, and a resonator structure is configured by the first electrode and the semi-transmissive reflective layer. The heights of the semi-transmissive reflective layers in the first light emitting element and the third light emitting element are the same.