Welding nanowires with light

RESEARCH at Stanford School of Engineering have found a way to weld together meshes of nanowires with light.

A lot of work is currently being done on nanoelectronics, and one of these is the creation of electrically conductive meshes made of metal nanowires. These meshes could one day be used in touchscreens, displays, LEDs and thin-film solar cells.

However, to create such a mesh, nanowires must be melded together in a crisscross pattern. Pressing them together or heating them damages the nanowires.

The Stanford engineers utilised plasmonics to fuse the wires using light. Plasmonics is the physics behind the interaction of light and metal in which the light flows across the surface of the metal in waves.

If two nanowires are placed to criss-cross each other, light generates Plasmon waves at the intersection, creating a hot spot. This fuses the nanowires, after which the hot spot disappears, preventing damage from residual heat.

This light-based, self-limiting, highly precise heating increases the control, speed and energy efficiency of nanoscale welding, easing the creation of nanowire meshes.

According to the researchers, the new technique could also allow mesh electrodes to be bound to flexible or transparent plastics and polymers. For example, they sprayed a solution containing silver nanowires in suspension on a plastic wrap and dried it.

Upon inspection after illumination, the spray had left an ultrathin layer of welded nanowires. The wrap was balled up, and found to maintain its electrical properties upon unwrapping. It also maintained most of its transparency.

Prior to the plasmonics approach, the plastic wrap holding the nanowires would have had to be heated to weld them together, destroying the substrate.

Welding nanowires with light

TAG:nanotechnology research and development