This shows an extruded spiral made of polymer-coated silicon-nanosheets glowing in UV light. Photo: Tobias Helbich/TUM.
This shows an extruded spiral made of polymer-coated silicon-nanosheets glowing in UV light. Photo: Tobias Helbich/TUM.

Silicon nanosheets are thin, two-dimensional (2D) layers possessing exceptional optoelectronic properties that are very similar to those of graphene, although the nanosheets are less stable. Now, researchers at the Technical University of Munich (TUM) in Germany have, for the first time ever, combined silicon nanosheets with a polymer to produce a composite material that is UV-resistant and easy to process. This advance, which is reported in papers in the Journal of Physics D: Applied Physics and Advanced Functional Materials, brings silicon nanosheets a significant step closer to industrial applications like flexible displays and photosensors.

Similar to carbon, silicon can form 2D networks that are only one atomic layer thick. Like graphene, for whose discovery Andre Geim and Konstantin Novoselov at the University of Manchester in the UK received the Nobel Prize in 2010, these layers possess extraordinary optoelectrical properties. Silicon nanosheets might thus find various applications in nanoelectronics, including 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-ion 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 chemist Tobias Helbich 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."

Helbich, in collaboration with fellow TUM chemist Bernhard Rieger, has for the first time successfully embedded the silicon nanosheets in a polymer, protecting them from both decay and 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 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."

The composite’s flexibility and durability against external influences also makes it amenable to standard polymer processing technology, putting practical applications within an arm's reach. For example, the composites are particularly well suited for applications in the up-and-coming field of nanoelectronics. Here, ‘classical’ electronic components like circuits and transistors are implemented on scales of less than 100nm, allowing the realization of whole new technologies, such as faster computer processors.

Alina Lyuleeva and Paolo Lugli from the Institute of Nanoelectronics at TUM, in collaboration with Helbich and Rieger, recently came up with the first successful application for the nanocomposite, by using it to create a novel photodetector. This involved mounting the polymer-embedded silicon nanosheets onto a silicon dioxide surface coated with gold contacts. Because of its Lilliputian dimensions, this kind of nanoelectronic detector saves a lot of space and energy.

This story is adapted from material from the Technical University of Munich, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.