Refractive Index Adjustment Layer for Display Sub-pixel Level Differences
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Solution Overview
Problem
In display devices with a resonator structure, variations in film thickness of the optical path adjustment layer between sub-pixels lead to level differences, affecting light extraction efficiency and color purity.
Innovation Solution
Incorporating a refractive index adjustment layer in at least one of the first or second electrodes of sub-pixels, allowing for optical path length adjustment to suppress level differences between sub-pixels, and forming a semi-transmissive reflective layer to cover the optical adjustment layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the film thickness of the optical path adjustment layer is varied according to the color type of sub-pixels to achieve resonance condition, then color reproducibility and light extraction efficiency are improved, but level difference between sub-pixels increases
Solution Approach 1:
The patent introduces a refractive index adjustment layer with different refractive indices in different regions corresponding to different color types of sub-pixels. This allows the optical path length to be adjusted locally for each color type (red, green, blue) without varying the physical film thickness, thereby maintaining a flat surface while achieving color-specific resonance conditions for improved light extraction efficiency
Solution Approach 2:
Instead of changing the physical dimension (film thickness) to adjust optical path length, the patent changes the optical parameter (refractive index) of the adjustment layer. By controlling the refractive index to be different in regions corresponding to different color types, the patent achieves different optical path lengths with the same physical thickness, resolving the contradiction between light extraction efficiency and surface flatness
2Reliability
If the film thickness of the optical path adjustment layer is varied according to the color type of sub-pixels, then resonance condition for each color type is satisfied, but manufacturing precision becomes more difficult
Solution Approach 1:
The patent employs a refractive index adjustment layer where the refractive index varies locally according to the color type of each sub-pixel region. This approach maintains a uniform film thickness across all sub-pixels, significantly simplifying the manufacturing process while still achieving color-specific resonance conditions through spatially varying refractive indices
Solution Approach 2:
The patent replaces the mechanical approach of varying film thickness with an optical approach of varying refractive index. This substitution eliminates the need for precise thickness control for each color type, as the resonance condition can be achieved by controlling the refractive index distribution instead, thereby improving manufacturability
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 reduces level differences between sub-pixels, enhancing light extraction efficiency and color purity by optimizing the optical path length for each sub-pixel type.
Implementation Method 1
a resonator structure that causes emitted light from the organic layer to resonate is formed
Implementation Method 2
a refractive index adjustment layer is included in at least one of the first electrode or the second electrode
Data Source
AI summary
Provided are a display device and an electronic device in which a level difference between front sub-pixels can be suppressed even if a resonator structure is included, and a method of manufacturing the display device. A display device includes a plurality of sub-pixels corresponding to a plurality of color types, in which each of the sub-pixels includes a light emitting element including a first electrode, an organic layer, and a second electrode, and in at least the sub-pixels corresponding to one color type, a resonator structure that causes emitted light from the organic layer to resonate is formed and a refractive index adjustment layer is included in at least one of the first electrode or the second electrode.