Block Copolymer Image Sensor for High Resolution and Low Crosstalk
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Solution Overview
Problem
CMOS image sensors face challenges in maintaining high photoelectric conversion efficiency and reducing crosstalk as pixel size decreases, leading to degraded image quality due to reduced light reception and increased signal interference.
Innovation Solution
An image sensor design incorporating a photoelectric conversion layer made of a block copolymer with electron donating and accepting blocks, which are phase-separated and connected to electrodes, enhancing pn junction stability and surface area, thereby improving photoelectric conversion efficiency and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase pixel density, then higher resolution is achieved, but photoelectric conversion efficiency deteriorates due to reduced light reception
Solution Approach 1:
The patent employs a block copolymer composite material consisting of electron-donating blocks and electron-accepting blocks. This composite structure creates multiple pn junctions within the photoelectric conversion layer, enabling effective charge separation even in small pixels with limited light reception, thereby maintaining high photoelectric conversion efficiency while achieving high resolution
Solution Approach 2:
The photoelectric conversion layer is segmented into multiple domains through block copolymer self-assembly, creating numerous pn junctions distributed throughout the layer. This segmentation increases the effective charge separation area, allowing small pixels to maintain high photoelectric conversion efficiency despite reduced light reception area
2Measurement precision
If pixel size is reduced to increase pixel density, then higher resolution is achieved, but crosstalk between pixels increases due to high aspect ratio
Solution Approach 1:
The block copolymer structure segments the photoelectric conversion layer into distinct electron-donating and electron-accepting domains, creating well-defined pn junctions that confine charge carrier separation to specific regions. This spatial confinement reduces electrical crosstalk between adjacent pixels while maintaining high resolution
Solution Approach 2:
The patent creates local pn junctions throughout the photoelectric conversion layer through block copolymer phase separation. These locally distributed junctions provide site-specific charge separation, reducing the need for long charge carrier transport paths and thereby minimizing electrical crosstalk between pixels
3Ease of manufacture
If conventional photoelectric conversion materials are used, then manufacturing is simpler, but photoelectric conversion efficiency is insufficient for small pixels
Solution Approach 1:
The patent changes the material parameter from conventional inorganic photoelectric conversion materials to organic block copolymer materials. This parameter change enables the formation of pn junctions through self-assembly, achieving high photoelectric conversion efficiency in small pixels while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
The block copolymer composite material combines electron-donating and electron-accepting blocks in a single polymer chain, enabling in-situ formation of pn junctions during film deposition. This approach achieves high photoelectric conversion efficiency without requiring complex multi-step manufacturing processes, thus maintaining ease of manufacture
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 solution enhances the image sensor's photoelectric conversion efficiency, extends its lifespan, and improves long-term reliability by effectively separating electron-hole pairs and reducing optical interference, resulting in improved image quality.
Implementation Method 1
a photoelectric conversion layer positioned between the first electrode and the second electrode... the photoelectric conversion layer includes a block copolymer composed of an electron donating block and an electron accepting block
Implementation Method 2
a color filter positioned on the second electrode of the light-sensing device
Data Source
AI summary
An example embodiment of the image sensor includes a light-sensing device including a first electrode, a second electrode disposed opposite to the first electrode, and a photoelectric conversion layer positioned between the first electrode and the second electrode. The photoelectric conversion layer includes a block copolymer including electron donating blocks and electron accepting blocks. The electron donating blocks are deposited together and connected to the first electrode and the second electrode. The electron accepting blocks are deposited together and connected to the first electrode and the second electrode. A color filter may be positioned on the second electrode of the light-sensing device.