Light-Driven Reversible
Modulation of Doping in Graphene
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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<sup>12</sup> cm<sup>–2</sup>. 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
