High-Refractive-Index Light Collection Layer for Blue QE Improvement
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Solution Overview
Problem
Optical elements with wave guide color filter (WGCF)-type structures experience a drop in quantum efficiency (QE) peak, particularly for blue color filters, due to lack of light from neighboring pixels, and struggle to maintain low cross-talk between color filters.
Innovation Solution
Incorporating a high-refractive-index light collection layer with a refractive index of 1.6 to 1.9, positioned above color filters, surrounded by a patterned second organic layer, which enhances the QE peak of blue color filters by up to 3.1% while maintaining low cross-talk and resembling QE peaks of composite metal grid (CMG)-type structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wave guide color filter (WGCF)-type structure is used, then the structure can guide light effectively, but the QE peak of blue color filters drops due to lack of light from neighboring pixels
Solution Approach 1:
The patent applies local quality by creating a light collection layer with high refractive index (1.6-1.9) specifically positioned above the blue color filter, while other regions maintain the original wave guide structure. This localized modification concentrates light collection capability where it is most needed (blue pixel) without disrupting the overall wave guide functionality, thereby improving blue QE peak while maintaining structural integrity.
Solution Approach 2:
The patent changes the refractive index parameter of the light collection layer to be higher than both the second organic layer and the blue color filter (n=1.6-1.9). This parameter change creates optimal light trapping conditions by maximizing the refractive index contrast, which enhances light collection efficiency from neighboring pixels and directs it into the blue color filter, thereby improving the QE peak.
2Illumination intensity
If a light collection layer with high refractive index is added, then the QE peak of blue color filter improves, but the device structure becomes more complex
Solution Approach 1:
The light collection layer is nested within the existing organic layer structure, specifically positioned between the second organic layer and the blue color filter. This nesting approach integrates the new high-refractive-index layer into the existing device architecture without requiring complete structural redesign, thereby improving blue QE peak while minimizing increases in overall device complexity.
Solution Approach 2:
The patent addresses the complexity issue by optimizing the lateral dimensions of the light collection layer. The layer is designed with a width less than half the width of the underlying color filter, creating a tapered or curved profile that reduces light scattering to neighboring pixels. This dimensional optimization maintains the QE improvement benefit while minimizing structural complexity and cross-talk.
3Illumination intensity
If the light collection layer width is increased to collect more light, then the QE peak improves, but cross-talk between color filters increases
Solution Approach 1:
The patent optimizes the width parameter of the light collection layer by setting it to less than half the width of the underlying color filter. This parameter optimization creates a balance: the layer is wide enough to collect sufficient light from neighboring pixels to improve the QE peak, but narrow enough to minimize lateral light spreading that would cause cross-talk between adjacent color filters.
Solution Approach 2:
The patent employs curved or tapered profiles for the light collection layer instead of straight vertical walls. This curvature design causes light rays to be redirected more effectively into the underlying blue color filter while reducing lateral light propagation to neighboring pixels. The curved profile thus improves light collection efficiency for the QE peak while simultaneously minimizing cross-talk between color filters.
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
The high-refractive-index light collection layer improves the QE peak of blue color filters significantly, maintaining low cross-talk between color filters and achieving QE peaks similar to CMG- and WGCF-type structures, with adaptable shapes and dimensions to suit various pixel configurations.
Implementation Method 1
The refractive index of the light collection layer is greater than that of the second organic layer... The refractive index of the light collection layer is greater than that of the color filter
Data Source
AI summary
An optical element is provided. The optical element includes a substrate, a plurality of metal grids formed on the substrate, a patterned first organic layer formed on the plurality of metal grids, a color filter surrounded by the patterned first organic layer, a second organic layer formed on the patterned first organic layer and the color filter, and a light collection layer surrounded by the second organic layer and corresponding to the color filter. The refractive index of the light collection layer is greater than that of the second organic layer. A method for fabricating the optical element is also provided.