The same kind of plastic used in Coke bottles becomes more useful

Aug 22, 2013 13:45 GMT  ·  By

Plastic is looked down upon as a polluting substance, yet it is used extensively in our industry, for juice bottles and chip bags to highly complex technologies. Right now, it's the latter we're looking at.

Ali Javey and colleagues at Berkeley University have revealed a method for printing carbon nanotube transistors on that very same sort of plastic (PET sheets).

The sheets of single-walled carbon nanotube thin-film transistors (SWCNT TFTs) are produced using inverse gravure printing.

That's a technique used to print magazines, cardboard boxes, catalogs, etc.

Why is this awesome? Because gravure printing is massively scalable. Printing presses can go through 14 meters of three-meter-wide reels of paper or plastic in a second.

Thus, printing carbon nanotubes can quickly lead to much cheaper electronics and wall-sized displays.

Head over to ExtremeTech for details, or read the research paper here. The short version? An “ink” of 99% semiconducting SWCNTs had to be made, to act as the channel. Then two other “inks” were used to make the other portions of the transistors: a silver ink for the source, drain and gate electrodes, and a high-k barium titanate ink for the dielectric.

The PET substrate is immersed in the solution of SWCNTs and is allowed to dry, creating a solid, uniform forest of CNTs — the transistor channel. This sheet is then run through the gravure printer multiple times. The first run deposits the source and drain electrodes (silver ink), the second deposits the high-k dielectric between the source and drain, and the last one adds a second silver gate electrode above the dielectric.