Making High-Quality, Lower-Cost Transistors for Flexible Electronics

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  A research team from DuPont and Cornell University has found a way to separate metallic and semiconducting carbon nanotubes, a discovery that may potentially work well with transistors used in flexible electronics applications.

The scientists, led by Research Fellow, Dr. Graciela B. Blanchet of DuPont and funded by the Air Force Office of Scientific Research, discovered a way to produce large amounts of organic semiconducting ink that can be transformed into thin, flexible electronics. When the research is complete, the tubes may be used in creating higher-quality, low-cost printable electronics.

"We have used DuPont's unique expertise in fluorine chemistry and Cornell's state of the art knowledge in device fabrication to tailor the conversion of metallic nanotubes and the simultaneous exfoliation of the nanotube ropes," said Blanchet.

Years ago, carbon nanotubes were recognized as being viable and even revolutionizing in the field of electronics. However, the metallic tubes could short-out the current path in transistors and that led scientists to find a way to achieve separation. Initially, they found that DNA could separate the metallic tubes from the semiconductors. Now, Blanchet's research team has discovered that they can separate the metallic and semiconducting nanotubes by attaching fluorinated molecules to their walls.

"It is unclear whether two carbon atoms of the tube connecting to two carbon atoms on the reactant molecule "kills" the metallic tubes or converts them to semi-conducting tubes," she said. "In either case, the huge reduction in metallic tubes prevents electrical shorts in the transistors and does not require further separation of nanotubes by type."

The researchers next steps are to focus on testing the semiconducting tubes in a variety of electronic devices such as solar cells while scaling up ink manufacturing.

"This work is a real breakthrough and will benefit many organic materials and devices such as solar cells and photodetectors where charge mobility is a limiting factor in their performances," said Dr. Charles Lee, program manager overseeing Blanchet's work for AFOSR.