Organic Imaging Element Buffer Layer for Low Dark Current
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Solution Overview
Problem
Existing organic imaging elements face challenges in achieving practical dark current and afterimage characteristics, which affect the signal-to-noise ratio and overall performance.
Innovation Solution
The use of an anode-side buffer layer with specific thiophene and carbazole-based materials in the imaging element, combined with a physical vapor deposition method, to improve dark current and afterimage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photoelectric conversion layer is positioned at a depth of 3 μm or more in a silicon semiconductor substrate to achieve sufficient light absorption, then photoelectric conversion efficiency is improved, but the aspect ratio of pixel size and depth increases leading to light leakage from adjacent pixels and limited light incidence angles
Solution Approach 1:
The patent changes the material parameter from inorganic silicon to organic semiconductor material, which has a much higher absorption coefficient (about 10^5 cm^-1 or higher) in the visible light range. This allows the photoelectric conversion layer to be positioned closer to the surface while maintaining sufficient light absorption, thereby reducing the aspect ratio and preventing light leakage from adjacent pixels.
2Reliability
If organic semiconductor material is used for photoelectric conversion to achieve high absorption coefficient and thinned photoelectric conversion layer, then sensitivity is improved and pixel miniaturization is enabled, but dark current characteristics and afterimage characteristics deteriorate
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the anode and the photoelectric conversion layer. This buffer layer mediates the interface properties, improving hole extraction efficiency and reducing dark current generation at the electrode interface, thereby addressing the dark current and afterimage characteristics issues while maintaining the high sensitivity benefits of organic semiconductor material.
3Quantity of substance
If miniaturization of pixel size progresses to improve recording density, then recording density is improved, but the aspect ratio of pixel size and depth increases leading to light leakage and limited light incidence angles
Solution Approach 1:
The patent changes the absorption coefficient parameter by switching from inorganic silicon to organic semiconductor material. This allows for a thinner photoelectric conversion layer while maintaining adequate light absorption, enabling pixel miniaturization and improved recording density without the light leakage problems that would otherwise result from high aspect ratios.
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 enhances dark current characteristics and afterimage performance, enabling improved sensitivity and miniaturization of the imaging element.
Implementation Method 1
the anode-side buffer layer includes a material having structural formula (I)... This configuration enhances dark current characteristics and afterimage performance
Implementation Method 2
combined with a physical vapor deposition method, to improve dark current and afterimage characteristics
Data Source
AI summary
An imaging element which is formed by sequentially stacking at least an anode, an anode-side buffer layer, a photoelectric conversion layer, and a cathode, in which the anode-side buffer layer includes a material having structural formulain which thiophene and carbazole are combined.