Organic Imaging Element Layer Stack for Low-Noise Photoelectric Conversion
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Solution Overview
Problem
The existing vertical spectroscopic imaging elements face challenges in achieving high image quality due to kTC noise and random noise, primarily because the organic photoelectric conversion section is not fully depleted, leading to increased noise levels.
Innovation Solution
Incorporating a first semiconductor layer with specific carbon-containing compounds between the organic layer and the second electrode, which has an electron affinity of 4.5 eV or more and 6.0 eV or less, to enhance adhesiveness and the electric field applied to the photoelectric conversion layer, thereby improving the manufacturing yield and element characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an organic photoelectric conversion section is used in a vertical spectroscopic imaging element, then the imaging element can detect light in the green wavelength range, but the organic photoelectric conversion section cannot be fully depleted, leading to increased kTC noise and random noise
Solution Approach 1:
A first semiconductor layer is introduced as an intermediary between the organic photoelectric conversion layer and the second electrode. This intermediate layer has an electron affinity of 4.5 eV or more and 6.0 eV or less, which is lower than the organic photoelectric conversion layer, enabling efficient electron extraction while maintaining full depletion of the organic layer and reducing noise.
Solution Approach 2:
The electron affinity parameter of the semiconductor layer is specifically controlled to be 4.5 eV or more and 6.0 eV or less. This parameter optimization ensures that the semiconductor layer can effectively extract electrons from the organic photoelectric conversion layer while maintaining full depletion, thereby reducing kTC noise and random noise.
2Reliability
If a first semiconductor layer with specific electron affinity is provided between the organic layer and the second electrode, then adhesiveness and electric field application are improved, but the device structure becomes more complex
Solution Approach 1:
The first semiconductor layer serves multiple functions simultaneously: it acts as an electron extraction layer, provides mechanical adhesion between the organic layer and second electrode, and enhances the electric field distribution. This multi-functionality reduces the need for additional separate layers, thereby limiting the increase in device complexity.
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
This configuration reduces dark current generation, enhances the response speed, and improves the overall image quality by ensuring better adhesiveness and electric field application to the photoelectric conversion layer.
Implementation Method 1
an organic layer provided between the first electrode and the second electrode and at least including a photoelectric conversion layer
Implementation Method 2
the first semiconductor layer having an electron affinity of 4.5 eV or more and 6.0 eV or less
Data Source
AI summary
An imaging element according to an embodiment of the present disclosure includes: a first electrode; a second electrode disposed to be opposed to the first electrode; an organic layer provided between the first electrode and the second electrode and at least including a photoelectric conversion layer; and a first semiconductor layer provided between the second electrode and the organic layer and having an electron affinity of 4.5 eV or more and 6.0 eV or less, the first semiconductor layer including a first carbon-containing compound and a second carbon-containing compound, the first carbon-containing compound having an electron affinity greater than 4.8 eV or an electron affinity greater than a work function of the second electrode, the second carbon-containing compound having an ionization potential greater than 5.5 eV.