Photoelectric Conversion Layer Noise Reduction via Segmented Electrode Design
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Solution Overview
Problem
Photoelectric conversion apparatuses face increased noise in signals due to varying capacitance, which affects the quality of photoelectrically converted signals, while maintaining a high aperture ratio is essential for efficient light conversion.
Innovation Solution
A photoelectric conversion apparatus with a photoelectric conversion unit comprising a first electrode, a second electrode, and a photoelectric conversion layer, where a member acts as a light guide with the layer, reducing parasitic capacitance by optimizing the surface areas and projections to minimize noise while maintaining a high aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the lower electrode extends from the pixel boundary portion to the pixel boundary portion to form a light guide with the photoelectric conversion layer, then the aperture ratio is improved, but the capacitance of the photoelectric conversion layer increases causing noise to increase
Solution Approach 1:
The lower electrode is divided into two distinct parts: a first lower electrode portion positioned at the pixel boundary portion with a first area, and a second lower electrode portion positioned inside the pixel with a second area. This segmentation allows the electrode to serve multiple functions - forming a light guide at the boundary while limiting capacitance increase within the pixel by controlling the area of the second portion.
Solution Approach 2:
Different portions of the lower electrode are designed with different areas and positions. The first lower electrode portion at the boundary has a larger area optimized for light guiding, while the second lower electrode portion inside the pixel has a controlled smaller area to minimize capacitance. This local differentiation resolves the contradiction between light guide effectiveness and noise reduction.
2Productivity
If the photoelectric conversion layer area is increased to improve light conversion efficiency, then the aperture ratio is improved, but the capacitance increases causing kTC noise to increase
Solution Approach 1:
The light guide function is moved from the pixel interior to the pixel boundary portion, utilizing the vertical/dimensional space at the edges. This allows the photoelectric conversion layer inside the pixel to maintain a smaller area for lower capacitance, while the light guide functionality is achieved through the lower electrode portions at the boundaries, effectively separating the light collection and charge accumulation functions in different spatial dimensions.
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 effectively reduces noise in the photoelectric conversion layer while preserving the high aperture ratio, enhancing the signal quality and efficiency of light conversion.
Implementation Method 1
a photoelectric conversion layer disposed between the first electrode and the second electrode
Implementation Method 2
a member that is in contact with the photoelectric conversion layer and that constitutes a light guide together with the photoelectric conversion layer
Data Source
AI summary
A photoelectric conversion apparatus includes a photoelectric conversion unit having a light incident surface and including: a first electrode; a second electrode disposed further toward the light incident surface; and a photoelectric conversion layer disposed between the first and second electrodes. The photoelectric conversion apparatus includes a member in contact with the photoelectric conversion layer and constituting a light guide together with the layer. An area of a first surface parallel to the light incident surface at a portion of the photoelectric conversion layer surrounded by the member is smaller than an area of a second surface disposed between the first surface and the second electrode at a portion of the photoelectric conversion layer surrounded by the member, and an area of orthogonal projection to the light incident surface of the first electrode is smaller than an area of orthogonal projection to the light incident surface of the second surface.