Polymer-coated silicon nanosheets could be an alternative to graphene

March 08, 2017 // By Christoph Hammerschmidt
Silicon nanosheets are thin, two-dimensional layers with extraordinal optoelectronic properties, much like graphene. However, they are instable by nature. A research team from Technische Universität München (TUM) has devised a composite material consisting of silicon nanosheets and a polymer that is resistant to ultraviolet light and easy to process. The discovery brings silicon nanosheets much closer to industrialization, for applications like flexible display panels or photosensors.

Similar to carbon, silicon can form two-dimensional networks that are just one atomic layer thick. Much like graphene, these nanosheets exhibit excellent optical properties. In theory, it could be used in nanoelectronic applications. Besides for flexible display panels or field effect transistors, the material could also be a candidate for anodes in lithium ion batteries. “Silicon nanosheets are particularly interesting because today our entire information technology is based on silicon. For industrial applications, it would not require to change over to a new basic material – in contrast to graphene,” explains TUM researcher Tobias Helbich. “However, these nanosheets are very fragile and disintegrate quickly when under UV radiation, which greatly limits their application.”

Along with other researchers, Helbig for the first time succeeded in embedding silicon nanosheets into a polymer and thus protect it from disintegration. The embedding process has a two-fold effective on the nanosheets: They are chemically modified and at the same time protected against oxidation. The development from the TUM 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 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 makes the newly developed material amenable to standard polymer technology for industrial processing. This puts actual applications within an arm’s reach.