Top Gate Polysilicon TFT Photosensitive Element
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Solution Overview
Problem
Existing photosensitive elements, particularly those made of amorphous silicon thin film transistors, have suboptimal sensitivity and performance, necessitating the development of a more effective light-intensity measurement solution using low-temperature polysilicon thin film transistors.
Innovation Solution
A photosensitive element comprising a first thin film transistor as a control switch and a second thin film transistor as a photosensitive unit, both of which are top gate type and made of low-temperature polysilicon, with a transparent gate region to expose the active layer for light intensity measurement, enhancing sensitivity and measurement efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon thin film transistors are used for photosensitive elements, then manufacturing is easier, but sensitivity and performance deteriorate
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to low-temperature polysilicon, which improves carrier mobility and photosensitive performance while maintaining low-temperature processing advantages. This parameter change resolves the contradiction by achieving both ease of manufacture and high sensitivity through material optimization.
2Reliability
If a traditional opaque gate structure is used, then transistor control is better, but light intensity measurement capability deteriorates
Solution Approach 1:
The patent applies local quality by making the gate structure partially transparent in specific regions while maintaining opaque control in other areas. The gate electrode includes transparent conductive oxide (TCO) portions that allow light transmission for sensing, while other portions provide electrical control, thus resolving the contradiction between control reliability and measurement capability.
Solution Approach 2:
The gate structure uses composite materials combining transparent conductive oxide (such as ITO, IZO, or IGZO) with metal layers. This composite structure provides both electrical conductivity for transistor control and optical transparency for light intensity measurement, simultaneously achieving reliable control and measurement precision.
3Measurement precision
If high sensitivity photosensitive elements are implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges the transistor gate structure with the photosensitive sensing structure into a single integrated component. The gate electrode serves dual functions: electrical control of the transistor and optical transmission for light sensing. This merging achieves high sensitivity without increasing device complexity, as the same structural elements perform multiple functions.
Solution Approach 2:
The gate structure is designed with multi-functionality, serving both as the electrical control element of the transistor and as the light transmission pathway for photosensitive detection. This universal design eliminates the need for separate control and sensing components, achieving high measurement precision while maintaining simple device architecture.
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 achieves high sensitivity and efficient light intensity measurement, extending the application scope of photosensitive elements and improving measurement speed and efficiency, particularly in display panels and X-ray imaging devices.
Implementation Method 1
A gate of the second thin film transistor includes a transparent region corresponding to at least a part of an active layer of the second thin film transistor, thereby achieving a measurement of a light intensity entering the second thin film transistor
Data Source
AI summary
The embodiments of the invention provide a photosensitive element, a display panel, a display device, and an X-ray imaging device. The photosensitive element includes a first top gate type thin film transistor as a control switch and a second top gate type thin film transistor serving as a photosensitive unit. The first top gate type thin film transistor is connected to the second top gate type thin film transistor. A gate of the second thin film transistor includes a transparent region corresponding to at least a part of an active layer of the second thin film transistor, thereby achieving a measurement of a light intensity entering the second thin film transistor when the first thin film transistor and the second thin film transistor are turned on simultaneously.