Organic Polymer Layer Blocks Holes in Radiation Detector
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Solution Overview
Problem
Radiation detecting systems face issues with high dark current and afterimage due to interface crystallization between electrode materials and amorphous-Se photoconductive layers, and insulating organic polymer layers fail to effectively block holes while transferring electrons.
Innovation Solution
A radiation detecting system is designed with a first electrode, a recording photoconductive layer, and an organic polymer layer containing a hole blocking material like carbon clusters or their derivatives, which blocks holes while allowing electron transfer, thereby reducing dark current and afterimage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an insulating organic polymer layer is used between the first electrode and the recording photoconductive layer to suppress interface crystallization, then interface crystallization is suppressed, but the layer fails to effectively block holes while transferring electrons, resulting in high dark current and afterimage
Solution Approach 1:
The patent introduces an organic polymer layer as an intermediary substance between the first electrode and the recording photoconductive layer. This layer mediates the interaction between the electrode and photoconductive layer, suppressing interface crystallization while maintaining proper charge transfer. The organic polymer acts as a buffer that prevents direct contact-induced crystallization but still allows functional operation.
Solution Approach 2:
The patent modifies the electrical parameters of the interface by introducing the organic polymer layer, which changes the conductivity characteristics and charge transfer properties. This parameter change enables the interface to block holes effectively while maintaining electron transfer capability, thereby reducing dark current and afterimage effects.
2Stability of the object's composition
If a suppressing layer of organic polymer is used to avoid interface crystallization, then interface crystallization is suppressed, but electric charges remain in the suppressing layer during repeated recording and readout, causing deterioration in sensitivity and ghost images
Solution Approach 1:
The organic polymer layer serves as a mediator that prevents charge accumulation at the interface. By introducing this intermediate layer, charges can pass through without being trapped, eliminating the ghost image problem while maintaining the crystallization suppression function.
Solution Approach 2:
The patent changes the charge transfer parameters at the interface by using organic polymer, which has specific electrical properties that prevent charge trapping. This parameter modification ensures that charges are efficiently transferred without remaining in the suppressing layer during repeated operations.
3Illumination intensity
If transparent oxide materials like ITO or IZO are used as electrode materials, then transparency is improved, but interface crystallization between the electrode material and a-Se is remarkably promoted
Solution Approach 1:
The patent introduces an organic polymer layer as an intermediary between the transparent oxide electrode and the amorphous-Se photoconductive layer. This intermediate layer prevents direct contact between the oxide electrode and a-Se, thereby suppressing interface crystallization while maintaining the transparency benefits of the oxide electrode material.
Solution Approach 2:
The patent applies local quality modification by introducing the organic polymer layer specifically at the interface region where crystallization occurs. This localized intervention protects the interface from crystallization without affecting the overall transparency of the electrode structure.
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 system achieves low dark current and suppressed afterimage by effectively blocking holes and transferring electrons, improving the overall electric characteristics.
Implementation Method 1
a recording photoconductive layer which generates electric charges in response to projection of the recording electromagnetic wave
Data Source
AI summary
In a radiation detecting system including a first electrode which is imparted with a positive bias and permeable to a recording electromagnetic wave carrying thereon image information, a recording photoconductive layer which generates electric charges in response to receipt of projection of the recording electromagnetic wave, an organic polymer layer provided between the first electrode and the recording photoconductive layer, and a second electrode which is provided on the side of the recording photoconductive layer opposite to a side where the first electrode is provided and being for recording the image information by storing electric charges generated in the recording photoconductive layer upon projection of the recording electromagnetic wave, the organic polymer layer includes a hole blocking material.