Using semiconducting polymer
ink, researchers at the Palo Alto Research Center
(Palo, Alto, CA) have developed the first plastic transistor
array entirely patterned using ink-jet printing
technology. The devices promise to enable the manufacture of flexible monitors, unbreakable cell phone and portable device displays, and wall-sized TVs.
In addition, the technology will also be able to create "smart" paper for electronic ink and RFID applications. The printed transistors meet all requirements for addressing displays: high mobility, low leakage, and good stability.
The technology builds upon the recent invention of polythiophene-based semiconducting polymer ink. The arrays are printed using an additive and a subtractive method, both requiring precise layer-to-layer registration, controlled by a computer vision system that ensures proper alignment even if the substrate warps or deforms during the procedure.
In a process analogous to the color registration performed in image printing, the layers of metal, dielectric, and semiconductor can conform to even flexible substrates. Jet-printed transistors made this way can match the performance of the same material deposited by conventional spin coating.
While more development is needed to make the jet-printed organic semiconductor display process ready for manufacture, it demonstrates that the devices can be made successfully