title: Magnetic assembly of transparent and conducting graphene-based functional composites.
abstract: Innovative methods producing transparent and flexible electrodes are highly sought in modern optoelectronic applications to replace metal oxides, but available solutions suffer from drawbacks such as brittleness, unaffordability and inadequate processability. Here we propose a general, simple strategy to produce hierarchical composites of functionalized graphene in polymeric matrices, exhibiting transparency and electron conductivity. These are obtained through protein-assisted functionalization of graphene with magnetic nanoparticles, followed by magnetic-directed assembly of the graphene within polymeric matrices undergoing sol-gel transitions. By applying rotating magnetic fields or magnetic moulds, both graphene orientation and distribution can be controlled within the composite. Importantly, by using magnetic virtual moulds of predefined meshes, graphene assembly is directed into double-percolating networks, reducing the percolation threshold and enabling combined optical transparency and electrical conductivity not accessible in single-network materials. The resulting composites open new possibilities on the quest of transparent electrodes for photovoltaics, organic light-emitting diodes and stretchable optoelectronic devices.
authors.affiliation: Complex Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: Hortense
authors.initials: H
authors.lastname: Le Ferrand
authors.affiliation: Food and Soft Materials, Department of Health Sciences and Technologies, ETH Zurich, Zurich 8092, Switzerland.
authors.forename: Sreenath
authors.initials: S
authors.lastname: Bolisetty
authors.affiliation: Complex Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: Ahmet F
authors.initials: AF
authors.lastname: Demirörs
authors.affiliation: Complex Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: Rafael
authors.initials: R
authors.lastname: Libanori
authors.affiliation: Complex Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: André R
authors.initials: AR
authors.lastname: Studart
authors.affiliation: Food and Soft Materials, Department of Health Sciences and Technologies, ETH Zurich, Zurich 8092, Switzerland.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Mezzenga