Polymer-coated silicon nanosheets as an alternative to graphene

March 09, 2017 // By Graham Prophet
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene, although nanosheets are less stable. Now, researchers at the Technical University of Munich (TUM) have produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This, say the researchers, is a significant step closer to industrial applications such as flexible displays and photosensors.

Similar to carbon, silicon forms two dimensional networks that are only one atomic layer thick. Like graphene, for whose discovery Andre Geim and Konstantin Novoselov received the Nobel Prize in 2010, these layers possess remarkable optoelectrical properties. Silicon nanosheets might find application in nanoelectronics, for example in flexible displays, field-effect transistors and photodetectors. With its ability to store lithium ions, it is also under consideration as an anode material in rechargeable lithium batteries.


“Silicon nanosheets are particularly interesting because today’s information technology builds on silicon and, unlike with graphene, the basic material does not need to be exchanged,” explains Tobias Helbich from the Wacker Chair for Macromolecular Chemistry at TUM. “However, the nanosheets themselves are very delicate and quickly disintegrate when exposed to UV light, which has significantly limited their application thus far.”


Now Helbich, in collaboration with Professor Bernhard Rieger, Chair of Macromolecular Chemistry, has for the first time successfully embedded the silicon nanosheets into a polymer, protecting them from decay. At the same time, the nanosheets are protected against oxidation. This is the first nanocomposite based on silicon nanosheets.


“What makes our nanocomposite special is that it combines the positive properties of both of its components,” explains Tobias Helbich. “The polymer matrix absorbs light in the UV domain, stabilizes the nanosheets and gives the material the properties of the polymer, while at the same time maintaining the remarkable optoelectronic properties of the nanosheets.”


Its flexibility and durability against external influences also makes the newly developed material amenable to standard polymer technology for industrial processing. This puts actual applications within reach.


The composites are particularly well suited for application in nanoelectronics. Here, “classical” electronic components like circuits and transistors are implemented on scales of less than 100 nanometers. This allows whole new technologies to be realized – for faster computer processors, for example.


The first successful application of the nanocomposite constructed by Helbich