May 2006

Flexible Displays

Carbon nanotubes are showing promise in flexible, low-power displays.

By Kevin Bullis

Carbon nanotubes' unique electronic properties make them promising as, among other things, ultra-efficient "electron emitters" for bright, low-power displays. Now, researchers have found a way to pattern nanotubes onto plastic sheets for flexible displays.

The new method, developed by researchers at Rensselaer Polytechnic Institute, Northeastern University, and New Mexico State University, starts with a surface prepatterned to specify where multiwalled nanotubes will grow on it. The researchers pour a liquid over the nanotubes and cook it until it forms a polymer. They then peel off the polymer and nanotubes. The polymer preserves the pattern right down to the positions of indi-vidual nanotubes, which it keeps aligned.

For displays, where single nanotubes must be isolated from others to get the best efficiencies, the researchers strip off a layer of polymer to expose the tips of nanotubes, then burn off long or tangled nanotubes, leaving isolated ones. "The results we've seen are some of the best that have been reported in the literature," says Swastik Kar, a postdoctoral researcher at RPI and a lead author of the paper. Prototype displays are still a few years off.