Nanotubes form transparent film

The key to making foldable computer displays is finding electrical components that conduct electricity well and are also transparent and flexible.

Researchers from the University of Florida at Gainesville and the Hungarian Academy of Sciences have found a way to make flexible, transparent films of single-walled carbon nanotubes that have a maximum amount of contact between nanotubes within the film, which makes the film a good electrical conductor.

Carbon nanotubes are rolled-up sheets of carbon atoms that can be smaller than a nanometer and have useful electrical and optical properties. A nanometer is one millionth of a millimeter, or the span of a row of 10 hydrogen atoms.

The film could eventually be used to make foldable computer displays, infrared cameras and line-of-sight optical communication devices.

The researchers made the films by suspending nanotubes in liquid, filtering them out using a membrane, then dissolving the membrane. The films have consistent thicknesses that can be controlled with nanoscale precision, according to the researchers. They have made films as large as 10 centimeters in diameter and 50 to 150 nanometers thick.

The 50-nanometer film transmits 70 percent of visible light and 90 percent of infrared light. The researchers used the film to make an optical field-effect transistor, which changes transparency in the presence of an electric field.

The method could be used practically within two years, according to the researchers. The work appeared in the August 27, 2004 issue of Science.