Radiation Sensor Stabilization via Organic Photoelectric Conversion
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Solution Overview
Problem
Thin film transistors using oxide semiconductors with active layers containing indium, gadolinium, and zinc experience unstable operation when irradiated with light of wavelengths 460 nm or less, leading to shifting threshold voltages and unstable radiation sensor performance.
Innovation Solution
A radiation sensor design incorporating a phosphor layer that converts incident radiation into distinct light components, with a first light component having a maximum peak wavelength greater than 460 nm and a second light component in the 400 nm to 460 nm range, which are then absorbed by an organic photoelectric conversion layer to reduce the intensity of the second light component reaching the oxide semiconductor active layer, thereby stabilizing the transistor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phosphor layer converts radiation into light components including wavelengths of 400 nm to 460 nm, then the radiation detection function is achieved, but the thin film transistor operation becomes unstable due to threshold voltage shifts
Solution Approach 1:
The patent introduces an organic photoelectric conversion layer as an intermediary between the phosphor layer and the thin film transistor. This layer selectively absorbs light components with wavelengths of 400 nm to 460 nm that would otherwise reach the oxide semiconductor active layer and cause threshold voltage shifts, while allowing other necessary light components to pass through for radiation detection functionality.
Solution Approach 2:
The patent converts the harmful light components (400-460 nm) that cause transistor instability into a beneficial function by using them to generate electrical signals through the organic photoelectric conversion layer. The layer absorbs these problematic wavelengths and converts them into usable electrical signals that contribute to the radiation detection output.
2Reliability
If additional filter layers are added to block harmful light, then transistor stability improves, but device complexity increases
Solution Approach 1:
The organic photoelectric conversion layer performs multiple functions simultaneously: it converts radiation to electrical signals for detection, selectively filters harmful light components (400-460 nm) to protect the thin film transistor, and contributes to the overall radiation detection sensitivity. This multi-functionality eliminates the need for separate filter layers.
Solution Approach 2:
The patent merges the radiation detection function and the light filtering function into a single organic photoelectric conversion layer. This layer combines the roles of what would traditionally require separate components, simplifying the overall device structure while maintaining both radiation detection capability and transistor protection.
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 design achieves stable operation of the radiation sensor by reducing the adverse effects of the second light component on the oxide semiconductor active layer, maintaining impact resistance and operational stability, and eliminating the need for additional filter layers, allowing for a simpler and more robust radiation sensor structure.
Implementation Method 1
a phosphor layer that converts incident radiation into converted light which contains a first light component having a first wavelength region that includes a maximum peak wavelength that is different from a maximum peak wavelength of the radiation
Implementation Method 2
an organic photoelectric conversion layer that photoelectrically converts the first light component to electricity
Data Source
AI summary
Provided is a radiation sensor comprising: a phosphor layer that converts incident radiation into converted light containing a first light component having a first wavelength region that includes a maximum peak wavelength different from a maximum peak wavelength of the radiation, and a second light component having a second wavelength region of 400 nm to 460 nm, different from that of the radiation and the first wavelength region; an organic photoelectric conversion layer; and an insulating substrate provided with a charge detection layer, and that includes a storage capacitor and a thin film transistor having an oxide semiconductor active layer, wherein the first and second light components each pass through the organic photoelectric conversion layer and arrive at the oxide semiconductor active layer, and wherein an intensity of the second light component is lower than an intensity of the first light component.