Dutch scientists at Delft University of Technology have developed a new plastics material that acts like a metal. The team attached a micrometer-thick organic polymer TTF crystal to a similarly thin organic crystal of the polymer TCNQ and discovered a 2 nanometer thick strip along the interface between the two crystals conducts electricity as well as a metal. This discovery could lead to a whole new way of making electronics from non-metallic materials, and even new superconductors.
Both TTF and TCNQ are electrical insulators. But Morpurgo's team found that a 2-nanometre-thick strip along the interface between the two crystals conducts electricity as well as a metal.
It was known that a blend of the two materials could conduct electricity, but it does so relatively poorly.
When laid side-by-side the two materials are physically unchanged, but the way electrons behave is subtly altered along the interface where the different materials are in close proximity, says Morpurgo. In tests, they tried cooling down the combined materials, expecting the odd behaviour to disappear because the two plastics become more insulating at lower temperatures.
Instead the interface became a better conductor, just as metals offer less resistance to electricity when they are cooled.
Usually the electrons inside each of the materials are unable to travel freely. But Morpurgo thinks that at the interface electrons from the TTF molecules are able to jump over to vacant spaces known as "holes" in the TCNQ molecules.