Electron Blocking Layer for Imaging Device Dark Current Reduction
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Solution Overview
Problem
Imaging devices suffer from increased dark current and reduced signal-to-noise ratio due to electron flow to the photoelectric conversion layer, even in the absence of light irradiation, which degrades image quality, especially in low-light conditions.
Innovation Solution
Incorporating an electron blocking layer containing carbon and chromium oxide between the first electrode and the photoelectric conversion layer, which suppresses electron movement and allows hole passage, thereby reducing dark current and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no electron blocking layer is used, then device structure is simple, but dark current increases and signal-to-noise ratio deteriorates
Solution Approach 1:
An electron blocking layer containing chromium oxide and carbon is introduced as an intermediary component between the first electrode and the photoelectric conversion layer. This layer specifically blocks electron flow from the first electrode to the photoelectric conversion layer while allowing hole transport, thereby reducing dark current and improving signal-to-noise ratio without compromising the overall device functionality
Solution Approach 2:
The electron blocking layer is constructed using a composite material system comprising chromium oxide and carbon. This composite structure leverages the electron-blocking properties of chromium oxide while carbon provides additional functionality in charge transport modulation, achieving effective dark current suppression while maintaining device performance
2Reliability
If electron blocking layer is added, then dark current decreases, but manufacturing process becomes more complex
Solution Approach 1:
The electron blocking layer's composition parameters are optimized by controlling the chromium oxide to carbon ratio and adjusting the layer thickness. By tuning these parameters, the layer achieves effective electron blocking while maintaining compatibility with existing manufacturing processes, thus improving dark current suppression without proportionally increasing manufacturing complexity
3Reliability
If electron blocking layer is implemented, then image quality improves, but device structure becomes more complex
Solution Approach 1:
The electron blocking layer serves as a specialized intermediary that selectively blocks electrons while permitting hole transport to the photoelectric conversion layer. This selective charge carrier blocking reduces dark current and improves image quality, particularly in low-light conditions, by preventing spurious electron flow that would otherwise create noise in the captured image
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 implementation of the electron blocking layer significantly decreases dark current and improves the signal-to-noise ratio, leading to enhanced image quality, particularly in low-light conditions, by preventing electron flow to the photoelectric conversion layer.
Implementation Method 1
an electron blocking layer that suppresses movement of electrons from the first electrode to the photoelectric conversion layer
Implementation Method 2
a photoelectric conversion layer that is arranged between the first electrode and the second electrode and converts light to charge
Data Source
AI summary
An imaging device includes a first electrode, a second electrode, a photoelectric conversion layer that is arranged between the first electrode and the second electrode, and an electron blocking layer that suppresses movement of electrons from the first electrode to the photoelectric conversion layer. The electron blocking layer contains carbon and an oxide of chromium and is arranged between the first electrode and the photoelectric conversion layer.