Flipping the Switch on Supramolecular Electronics

Graphene Flagship partners at the University of Strasbourg and CNRS (France), together with associated members at the University of Mons (Belgium) and collaborators the Humboldt University of Berlin (Germany) and the University of Trento (Italy), successfully combined photoswitchable molecular lattices with layered materials to create new high-performance devices that show macroscopic responses to light.
 
Graphene and related materials hold great potential for technological applications such as electronics, sensors and energy storage devices, among others. Due to their high surface sensitivity, these materials are an ideal platform to study the interplay between molecular assemblies at the nanoscale and macroscopic electrical phenomena.
 
Researchers within the Graphene Flagship designed a molecule that can reversibly undergo chemical transformations when illuminated with ultraviolet and visible light. This molecule –a photoswitchable spiropyran– can be then anchored to the surface of materials such as graphene or molybdenum disulfide, thus generating an atomically precise hybrid macroscopic superlattice. When illuminated, the whole supramolecular structure experiences a collective structural rearrangement, which could be directly visualized with a sub-nanometer resolution by scanning tunneling microscopy.
 
More importantly, this light-induced reorganization at the molecular level induces large changes in the macroscopic electrical properties of the hybrid devices. The molecules, together with the layers of graphene and related materials, can convert single-molecule events into a spatially homogeneous switching action that generates a macroscopic electrical response. This novel and versatile approach takes supramolecular electronics to the next level.
 
“Thanks to this new approach, we can exploit the capacity of collective switching events occurring in superlattices of photochromic molecules assembled onto graphene and related materials to induce large scale and reversible modulation in the electrical properties of high-performance opto-electronic devices,” said Paolo Samorì, lead author of the paper. “This technology could find applications in the next generation of smart and portable electronics, with programmable properties.”
 
Vittorio Pellegrini, researcher at IIT and Division Leader for Energy, Composites, and Production at the Graphene Flagship, highlighted how the research is “unique in the way it combines graphene and other related materials with light-responsive chemical molecules. These macroscopic arrangements are promising platforms for optoelectronics.”
 
These advances, made possible by the collaborative environment of the Graphene Flagship, could lead to promising applications in sensors, optoelectronics, and flexible devices. Researchers now dream of high-performance multifunctional hybrid devices under control of nature’s most abundant and powerful source of energy – light.
 
“Supra-molecular chemistry has been part of the Flagship research since the very beginning,” Professor Andrea C. Ferrari, science and technology officer of the Graphene Flagship and chair of its management panel, added. “Over the years our partners have improved and developed the techniques that enable to interface molecules with graphene and related materials. We are now witnessing a steady progress towards applications, as shown by this interesting work.”
 
Reference
 
Collective molecular switching in hybrid superlattices for light-modulated two-dimensional electronics.
 
Marco Gobbi, Sara Bonacchi, Jian X. Lian, Alexandre Vercouter, Simone Bertolazzi, Björn Zyska, Melanie Timpel, Roberta Tatti, Yoann Olivier, Stefan Hecht, Marco V. Nardi, David Beljonne, Emanuele Orgiu & Paolo Samorì. Nature Communications, 2018, 9, 2661 DOI: 10.1038/s41467-018-04932-z.