title: Light-driven reversible modulation of doping in graphene.
abstract: We report a route to noncovalently latch dipolar molecules on graphene to create stable chromophore/graphene hybrids where molecular transformation can be used as an additional handle to reversibly modulate doping while retaining high mobilities. A light switchable azobenzene chromophore was tethered to the surface of graphene via π-π interactions, leading to p-doping of graphene with an hole concentration of ~5 × 10(12) cm(-2). As the molecules switch reversibly from trans to cis form the dipole moment changes, and hence the extent of doping, resulting in the modulation of hole concentration up to ~18% by alternative illumination of UV and white light. Light-driven conductance modulation and control experiments under vacuum clearly attribute the doping modulation to molecular transformations in the organic molecules. With improved sensitivities these "light-gated" transistors open up new ways to enable optical interconnects.
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Myungwoong
authors.initials: M
authors.lastname: Kim
authors.forename: Nathaniel S
authors.initials: NS
authors.lastname: Safron
authors.forename: Changshui
authors.initials: C
authors.lastname: Huang
authors.forename: Michael S
authors.initials: MS
authors.lastname: Arnold
authors.forename: Padma
authors.initials: P
authors.lastname: Gopalan
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D003460:Crystallization / Q000379:methods*; D006108:Graphite / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry / Q000528:radiation effects; D008422:Materials Testing; D008968:Molecular Conformation / Q000528:radiation effects; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D046911:Macromolecular Substances; C009495:titanium dioxide; D006108:Graphite; D014025:Titanium; C009850:azobenzene