Scientists have been struggling for more than a decade to find a way of making wires so small that electrons passing through them have almost no room to wobble from side to side. Having to stay on the straight-and-narrow would speed the electrons along—which is important to engineers trying to squeeze out every last bit of performance from their electronics—and it would make the wires more efficient. Samson Jenekhe, a chemical engineer at the University of Rochester in New York, realized that the long, thin molecules of semiconducting polymers would be just the right dimensions for such quantum wires.
The trick was how to isolate one long polymer molecule. Jenekhe first tried to isolate the strands from one type of polymer—call it B—by mixing them into a second polymer, A. The idea was for the B molecules to serve as wires, and the A molecules to provide the insulation. It didn’t work: the B molecules clumped together, allowing electrons to jump from strand to strand. Jenekhe next tried a more elaborate technique. He chemically attached a strand of A to each end of the B molecule, creating a single polymer that was two-thirds A and one-third B. Then he took individual molecules of this hybrid and suspended them in a block of A. This time it worked.
Although scientists had already made quantum wires with traditional semiconductors such as silicon or gallium arsenide, these materials are difficult and costly to work with. Jenekhe’s wires, by contrast, can be made with simple chemistry, he says. Polymer wires will be a lot cheaper, both in material cost and in fabrication costs. In several years, they might find their way into ultra-sensitive light detectors for medical use, new laser, and maybe even a super-sensitive electronic camera.