Stacked Image Sensor Infrared Sensitivity
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Solution Overview
Problem
Image sensors face challenges in achieving both small size and high sensitivity, especially under low illumination, as smaller pixels reduce absorption areas and sensitivity.
Innovation Solution
The design incorporates a first photoelectronic device for visible light and a second photoelectronic device for infrared light, stacked vertically without a color filter, using a silicon substrate with blue, red, and green photodiodes, and an organic photoelectronic device with a green light absorption layer, along with an infrared light absorption layer, to enhance sensitivity and luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pixel size is reduced to achieve smaller image sensor size, then the image sensor size is reduced, but the absorption area becomes smaller and sensitivity deteriorates
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked architecture, placing the infrared photoelectronic device vertically above the visible light photoelectronic device. This vertical stacking enables multi-spectral sensing (visible and infrared) within the same pixel footprint, effectively increasing the functional absorption area without expanding the sensor's planar dimensions, thus maintaining sensitivity while reducing overall sensor size.
Solution Approach 2:
The patent divides the photoelectronic sensing function into distinct spectral segments: a first photoelectronic device for visible light wavelengths and a second photoelectronic device for infrared wavelengths. Each segmented device is optimized for its specific wavelength range, allowing both to coexist in a compact stacked configuration without spectral interference, thereby preserving sensitivity across multiple bands in a small form factor.
2Measurement precision
If the pixel size is reduced to achieve high resolution, then the resolution is improved, but the absorption area becomes smaller and luminance deteriorates under low illumination
Solution Approach 1:
The stacked photoelectronic device structure provides multi-functionality by enabling simultaneous detection of visible light and infrared radiation within each pixel. This universal sensing capability allows the small pixel to capture a broader spectrum of light information, improving luminance performance under low illumination conditions while maintaining high resolution through the compact stacked design.
3Adaptability or versatility
If a color filter is added to achieve color separation, then the color sensing capability is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the color filter layer from the traditional sensor architecture. Instead of using color filters to separate wavelengths, the invention directly employs wavelength-selective photoelectronic materials in the stacked devices that inherently respond to specific spectral bands (visible and infrared), simplifying the overall device structure while maintaining color and spectral sensing capability.
Solution Approach 2:
The patent replaces the mechanical/optical filtering approach (color filters that physically block certain wavelengths) with a material-based approach where the photoelectronic devices themselves are engineered to selectively absorb specific wavelength ranges. This substitution eliminates the need for additional filter layers and reduces structural complexity while preserving spectral discrimination capability.
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 maintains sensitivity and luminance without increasing the image sensor's area, even under low illumination, and allows for high sensitivity and luminescence characteristics by utilizing the second photoelectronic device's infrared sensitivity.
Implementation Method 1
A photoelectronic device converts light into an electrical signal using photoelectronic effects
Implementation Method 2
the second photoelectronic device senses light in an infrared region
Implementation Method 3
the visible light absorption layer may selectively absorb light in one of the blue wavelength region, the red wavelength region, and the green wavelength region
Implementation Method 4
an infrared light absorption layer, to enhance sensitivity and luminance
Data Source
AI summary
Image sensors, and electronic devices including the image sensors, include a first photoelectronic device including at least one of a blue photoelectronic device sensing light in a blue wavelength region, a red photoelectronic device sensing light in a red wavelength region, and a green photoelectronic device sensing light in a green wavelength region, and a second photoelectronic device stacked on one side of the first photoelectronic device without being interposed by a color filter, wherein the second photoelectronic device senses light in an infrared region.