Flexible Electronics Benefit from New Materials

Carbon nanotubes with polar encapsulation show promising performance.

Flexible electronics have been in the works for years. Some of the promises of this technology include wearable devices, foldable displays and unique space-saving designs. Making electronics elastic is a substantial challenge, but new materials may make it possible sooner rather than later.

Display hardware has come along way since CRTs, but even modern LCD technology requires rigid glass packaging to keep pixels positioned. Rigid construction is ideal from a structural standpoint, as the electronic structures are not subject to excessive or varying forces under normal operation.

If you want a flexible product, on the other hand, you have to accept that components will be under varying amounts of tension or compression depending on the direction the device is bent. Even after relatively few loading cycles, most traditional electronic materials will fail.

New materials are part of the game, and carbon nanotubes (CNTs), among their many other uses, have the potential to enable more robust flexible electronics. Even CNTs have their drawbacks, one of which is a sensitivity to impurities which can greatly reduce performance.

Researchers at the University of Texas at Austin and Northwestern University have come up with a new way to incorporate CNTs into flexible devices with improved performance. As described in a UT Austin News release, the team has applied a new material to encapsulate the CNTs.

The material is polyvinyledenedifluoride-tetrafluoroethylene. Even the abbreviation, PVDF-TrFE, is long. Fortunately, it is not the name that counts. Instead, it is the polarity of the molecule that allows for the improvements.

The project leader, Prof. Ananth Dodabalapur of the Department of Electrical and Computer Engineering at UT Austin, describes it this way, “We attribute the improvements to the polar nature of PVDF-TrFE that mitigates the negative effect of impurities and defects on the performance of semiconductor single-walled carbon nanotubes.”

He explains why, “These impurities can act as charged defects that trap charge carriers in semiconductors and reduce carriers’ mobility, which eventually could deteriorate the performance of transistors.”

The research included testing of transistors and circuits made from the combination. Marked improvements were noted and attributed to the use of PVDF-TrFE. This hypothesis was confirmed by comparison with nonpolar alternatives which did not perform as well. Extension of the method to more complex circuitry is planned for future work.


Image Credit: S. Jang and A. Dodabalapur/University of Texas at Austin