Thiophene Derivative CMOS Image Sensor Eliminates Color Filters
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Solution Overview
Problem
Conventional CMOS image sensors suffer from reduced sensitivity due to the absorption of approximately ⅔ of incident light by color filters, which also complicate the manufacturing process and require additional components like micro lenses.
Innovation Solution
A vertically-stacked CMOS image sensor using thiophene derivatives as photoelectric conversion units, specifically p-type and n-type thiophene layers forming a P-N heterojunction, which absorb blue, green, and red light without the need for color filters or micro lenses, with additional layers like electron and hole blocking layers enhancing light absorption and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color filters are used in the photodiode to detect specific wavelengths, then wavelength selectivity is improved, but light absorption is reduced by approximately 2/3 and sensitivity deteriorates
Solution Approach 1:
The invention extracts and removes the color filter component from the conventional photodiode structure. By eliminating the color filter that blocks 2/3 of incident light, the patent achieves full-spectrum light detection while maintaining wavelength selectivity through the photoelectric conversion characteristics of the photodiode material itself, thereby improving sensitivity without sacrificing manufacturing ease
Solution Approach 2:
The photodiode is designed to perform multiple functions: it detects all wavelengths of incident light (blue, green, red) simultaneously and also performs signal processing functions. This multi-functional design eliminates the need for separate color filter components while maintaining the ability to distinguish different wavelengths through the photodiode's inherent photoelectric conversion properties
2Adaptability or versatility
If color filters are added to the photodiode structure, then wavelength detection capability is improved, but device complexity increases and additional components like micro lenses are required
Solution Approach 1:
The invention merges the wavelength detection function directly into the photodiode structure by utilizing the photoelectric conversion characteristics of the photodiode material for different wavelength ranges. This integration eliminates the need for separate color filter layers and micro lens components, thereby maintaining full-color detection capability while significantly reducing device complexity and structural layers
Solution Approach 2:
The photodiode structure is designed to universally detect all visible wavelengths (blue, green, red) simultaneously through its material properties, rather than requiring separate detection paths for each wavelength. This universal detection capability is achieved without adding complex filtering structures, thus maintaining versatility while simplifying the overall device architecture
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 CMOS image sensor achieves improved sensitivity and stability by directly converting light into electrical signals without color filters, simplifying the manufacturing process and increasing the sensor's stability against moisture and oxygen, while maintaining a compact structure.
Implementation Method 1
the first photoelectric conversion unit detects blue light and comprises: a first electrode; a second electrode; and a p-type thiophene derivative layer between the first electrode and the second electrode
Data Source
AI summary
Provided is a CMOS image sensor that uses thiophene derivatives. The CMOS image sensor includes first through third photoelectric conversion units vertically and sequentially stacked on a semiconductor substrate. The first photoelectric conversion unit detects blue light and comprises a first electrode, a second electrode, and a p-type thiophene derivative layer between the first electrode and the second electrode.