Semiconducting Polymer Separation of Carbon Nanotubes
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Solution Overview
Problem
Current methods for producing semiconducting single-walled carbon nanotubes (SWNTs) result in mixtures containing both semiconducting and metallic SWNTs, making it difficult to achieve high-purity semiconducting SWNTs suitable for applications like organic photovoltaic devices and field effect transistors, as existing separation methods are not scalable.
Innovation Solution
A process involving the use of a semiconducting polymer with a band gap in the range of 0.5 to 1.8 eV, dispersed in an aromatic solvent, to separate semiconducting SWNTs from metallic SWNTs through centrifugation, achieving a composition suitable for forming high-performance semiconducting layers in electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional growth methods (arc discharge or laser ablation) are used to produce SWNTs, then SWNTs can be manufactured, but the product contains mixtures of semiconducting and metallic SWNTs that cannot be easily separated
Solution Approach 1:
The patent uses a semiconducting polymer as an intermediary dispersant that selectively binds to semiconducting SWNTs through pi-pi stacking interactions. This mediator enables separation by causing semiconducting SWNTs to precipitate while metallic SWNTs remain dispersed in the supernatant, solving the purity problem without requiring complex purification steps
Solution Approach 2:
The patent changes the chemical and physical parameters of the SWNT dispersion system by introducing a semiconducting polymer with specific band gap (0.5-1.8 eV) and molecular weight (10,000-1,000,000 g/mol). This parameter change creates selective precipitation behavior based on the electronic structure match between the polymer and semiconducting SWNTs, enabling separation from metallic SWNTs
2Manufacturing precision
If existing separation methods are used to remove metallic SWNTs, then some purification can be achieved, but the methods are not suitable for large-scale technological processes
Solution Approach 1:
The semiconducting polymer performs dual functions: it acts as both a dispersant and a separation agent. The polymer selectively binds to semiconducting SWNTs and causes their precipitation, enabling the system to self-separate without requiring additional complex equipment or multiple processing steps, making it scalable to large production
Solution Approach 2:
The patent exploits phase transition in the dispersion system by inducing precipitation of semiconducting SWNTs through polymer addition. The semiconducting SWNTs transition from dispersed state to precipitated state, while metallic SWNTs remain in the supernatant phase, enabling simple separation by centrifugation or filtration that scales well
3Ease of operation
If non-semiconducting polymers are used as dispersants, then SWNTs can be dispersed, but selectivity for separating semiconducting from metallic SWNTs is insufficient
Solution Approach 1:
The patent applies local quality by selecting polymers with specific local electronic properties (band gap of 0.5-1.8 eV) that match the electronic structure of semiconducting SWNTs. This localized electronic compatibility creates strong pi-pi stacking interactions specifically with semiconducting SWNTs, providing high selectivity while maintaining good dispersion capability
Solution Approach 2:
The patent changes the electronic parameter (band gap) of the dispersant polymer to match the electronic structure of semiconducting SWNTs. This parameter matching creates selective binding through pi-pi stacking, enabling the polymer to distinguish between semiconducting and metallic SWNTs based on their electronic properties rather than just physical properties
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 process effectively separates semiconducting SWNTs from metallic SWNTs, resulting in a composition that enhances charge carrier mobility and on/off ratio in organic field effect transistors, meeting the requirements for advanced electronic devices.
Implementation Method 1
followed by centrifugation
Implementation Method 2
dispersing semiconducting SWNTs and metallic SWNTs with polymer
Data Source
AI summary
Provided is a process for preparing a composition comprising semiconducting single-walled carbon nanotubes, a semiconducting polymer and solvent A (composition A), which process comprises the step of separating composition A from a composition comprising semiconducting and metallic single-walled carbon nanotubes, the semiconducting polymer and solvent B (composition B), wherein the semiconducting polymer has a band gap in the range of 0.5 to 1.8 eV and solvent A and B comprise an aromatic or a heteroaromatic solvent, composition A itself, a process for forming an electronic device, which process comprises the step of forming a layer by applying composition A to a precursor of the electronic device, as well as the electronic device obtainable by this process.