Carbon Nanotube Thin Film Transistor with Oriented Segments
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Solution Overview
Problem
Conventional carbon nanotube-based thin film transistors face issues with non-uniform dispersion of carbon nanotubes, residual organic solvent impurities, low carrier mobility, and inflexibility due to aggregation and printing methods, limiting their practical application.
Innovation Solution
A thin film transistor design featuring a semiconducting carbon nanotube layer with aligned carbon nanotubes joined by van der Waals forces, integrated into a top or bottom gate structure on a flexible substrate, enhancing carrier mobility and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If carbon nanotubes are printed as a mixture with polymer on substrate, then semiconducting layer can be formed, but carbon nanotubes aggregate and cannot be uniformly dispersed
Solution Approach 1:
The patent extracts carbon nanotubes from their aggregated mixture state and separates them into individual nanotubes through sonication and filtration processes. This extraction of nanotubes from the polymer mixture allows for uniform dispersion while maintaining the ease of printing fabrication method.
Solution Approach 2:
The patent segments the carbon nanotube structure into individual nanotubes rather than using them as aggregated bundles. By separating and dispersing individual nanotubes in the polymer matrix, the patent achieves uniform dispersion throughout the semiconducting layer while preserving the printing fabrication approach.
2Manufacturing precision
If organic solvent is used in carbon nanotube printing, then carbon nanotube layer can be formed, but solvent is hard to eliminate and impurities remain
Solution Approach 1:
The patent uses water-soluble polymers that allow for rapid evaporation of water solvent rather than using traditional organic solvents. This skipping of the problematic organic solvent elimination step enables quick drying without residual impurities, achieving high purity while maintaining ease of manufacture.
Solution Approach 2:
The patent changes the solvent parameter from organic solvents to water, which has different evaporation characteristics. Water evaporates completely without leaving residual impurities, thereby improving the purity of the carbon nanotube layer while simplifying the drying process.
3Reliability
If conventional printing method is used for carbon nanotube layer, then fabrication is simple, but carbon nanotubes lack high carrier mobility and transistor is inflexible
Solution Approach 1:
The patent performs preliminary alignment of carbon nanotubes along the channel direction before finalizing the semiconducting layer structure. This preliminary orientation action ensures that nanotubes are positioned to maximize carrier mobility along the current flow direction, achieving high reliability without excessive fabrication complexity.
Solution Approach 2:
The patent creates a composite material structure where aligned carbon nanotubes are embedded in a flexible polymer matrix. This composite approach combines the high carrier mobility of oriented nanotubes with the flexibility of the polymer, achieving both high reliability and mechanical flexibility while maintaining relatively simple fabrication.
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 carrier mobility exceeding 10 cm2/V−1s−1 and flexibility, with improved durability and on/off current ratios, addressing the limitations of previous carbon nanotube-based transistors.
Implementation Method 1
A thin film transistor is provided, having a semiconducting layer, a source electrode and a drain electrode connected to the semiconducting layer, an insulating layer located between the semiconducting layer and a gate electrode, wherein the semiconducting layer includes a plurality of successive and oriented carbon nanotube segments joined end-to-end by van der Waals attractive force
Data Source
AI summary
A thin film transistor includes a source electrode, a drain electrode, a semiconducting layer, and a gate electrode. The drain electrode is spaced from the source electrode. The semiconducting layer is connected to the source electrode and the drain electrode. The gate electrode is insulated from the source electrode, the drain electrode, and the semiconducting layer by an insulating layer. The semiconducting layer comprises at least two stacked carbon nanotube films, and each carbon nanotube film comprises a plurality of carbon nanotubes primarily oriented along a same direction, and the carbon nanotubes in at least two adjacent carbon nanotube films are aligned along different directions.