Imaging Device Photoelectric Converter Voltage Control
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Solution Overview
Problem
Conventional imaging devices using silicon substrates face limitations in sensitivity to long wavelength light due to physical properties, particularly in the near-infrared and infrared ranges, and struggle to achieve uniform spectral sensitivity across different wavelength bands.
Innovation Solution
An imaging device with a photoelectric converter structure comprising a first and second photoelectric conversion layer, where the first layer has an absorption peak at a visible wavelength and the second layer at an infrared wavelength, with a voltage application circuit to change spectral sensitivity characteristics by adjusting the voltage between the layers, allowing for switchable sensitivity between visible and infrared ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon substrate is used for the image sensor, then the device can be manufactured with established processes, but the sensitivity to long wavelength light (near-infrared and infrared ranges) is limited due to physical property limitations of silicon
Solution Approach 1:
The patent uses a composite structure combining silicon substrate with organic photoelectric conversion materials. The silicon substrate provides mechanical support and short-wavelength detection, while the organic layers (first and second photoelectric conversion layers) provide enhanced near-infrared and infrared sensitivity, creating a multi-material system that overcomes the limitations of pure silicon
Solution Approach 2:
The patent adds a vertical dimension to the imaging structure by stacking organic photoelectric conversion layers on top of the silicon substrate. This multi-layer vertical architecture allows different materials to detect different wavelength ranges, expanding the spectral sensitivity without compromising the established silicon manufacturing process
2Reliability
If a photoelectric convertor using organic material is stacked with a silicon-based photoelectric convertor, then sensitivity to near-infrared light is improved, but the spectral sensitivity cannot be made uniform across different wavelength ranges due to the specific absorption spectrum of the organic material
Solution Approach 1:
The patent applies voltages dynamically to the first and second photoelectric conversion layers to control their spectral sensitivity characteristics. By adjusting the applied voltages, the device can switch between different sensitivity modes (e.g., visible-light dominant, near-infrared dominant, or balanced mode), making the spectral response adaptable rather than fixed
Solution Approach 2:
The patent changes the electrical parameters (voltages) applied to the organic photoelectric conversion layers to control their absorption characteristics. By varying the voltage, the spectral sensitivity of the organic layers can be tuned to achieve uniform overall spectral response across visible and infrared ranges
3Manufacturing precision
If voltages are applied to pixels individually to obtain uniform spectral sensitivity in RGB color imaging, then spectral uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent designs the voltage application circuit to control multiple photoelectric conversion layers simultaneously with a unified control scheme. The same voltage control mechanism serves both to adjust spectral sensitivity and to enable switching between different imaging modes, reducing the need for separate control circuits for each function
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 device achieves enhanced sensitivity and switchable spectral sensitivity, enabling effective image capture in both visible and infrared ranges by adjusting the applied voltage, thereby improving imaging capabilities in various lighting conditions.
Implementation Method 1
a first photoelectric conversion layer disposed between the first electrode and the second electrode and containing a first material having an absorption peak at a first wavelength
Implementation Method 2
a second photoelectric conversion layer disposed between the first photoelectric conversion layer and the second electrode and containing a second material having an absorption peak at a second wavelength different from the first wavelength
Implementation Method 3
a photoelectric converter that converts incident light into electric charges
Data Source
AI summary
An imaging device includes at least one unit pixel cell including a photoelectric converter that converts incident light into electric charges. The photoelectric converter includes: a first electrode; a light-transmitting second electrode; a first photoelectric conversion layer disposed between the first electrode and the second electrode and containing a first material having an absorption peak at a first wavelength; and a second photoelectric conversion layer disposed between the first photoelectric conversion layer and the second electrode and containing a second material having an absorption peak at a second wavelength different from the first wavelength. The absolute value of the ionization potential of the first material is larger by at least 0.2 eV than the absolute value of the ionization potential of the second material.