Floating evaporative assembly of aligned carbon nanotubes
High density films of semiconducting single-walled carbon nanotubes having a high degree of nanotube alignment are provided. Also provided are methods of making the films and field effect transistors (FETs) that incorporate the films as conducting channel materials. The single-walled carbon nanotubes are deposited from a thin layer of organic solvent containing solubilized single-walled carbon nanotubes that is spread over the surface of an aqueous medium, inducing evaporative self-assembly upon contacting a solid substrate.
1. A method of forming a film of aligned semiconducting-Single Wall Carbon Nanotube (s-SWCNTs) on a substrate, the method comprising:
(a) spreading a liquid solution comprising semiconductor-selective- polymer-wrapped s-SWCNTs dispersed in an organic solvent across the surface of a hydrophobic substrate, wherein the concentration of semiconductor-selective-polymer-wrapped s-SWCNTs in the liquid solution is no greater than 50 μg/ml; and
(b) withdrawing the hydrophobic substrate from the liquid solution, wherein the semiconductor-selective-polymer-wrapped s-SWCNTs from the liquid solution are deposited as a film of aligned semiconductor-selective-polymer-wrapped s-SWCNTs on the hydrophobic substrate;
wherein the hydrophobic substrate is withdrawn from the liquid solution, and the film of aligned semiconductor-selective-polymer-wrapped s-SWCNTs is formed, at a rate of at least 1 mm/min and further wherein the film of aligned semiconductor-selective-polymer-wrapped s-SWCNTs has a s-SWCNT linear packing density of at least 35 s-SWCNTs/μm.
2. The method of claim 1 , wherein the concentration of semiconductor-selective-polymer-wrapped s-SWCNTs in the liquid solution is no greater than 10 μg/ml.
3. The method of claim 1 , wherein the concentration of semiconductor-selective-polymer-wrapped s-SWCNTs in the liquid solution is in the range from 1 μg/ml to 50 μg/ml.
4. The method of claim 1 , wherein the concentration of semiconductor-selective-polymer-wrapped s-SWCNTs in the liquid solution is in the range from 1 82 g/ml to 10 μg/ml.
5. The method of claim 1 , wherein the hydrophobic substrate is withdrawn from the liquid solution, and the film of aligned semiconductor-selective-polymer-wrapped s-SWCNTs is formed, at a rate of at least 5 mm/min.
6. The method of claim 5 , wherein the concentration of semiconductor-selective-polymer-wrapped s-SWCNTs in the liquid solution is in the range from 1 μg/ml to 50 μg/ml.