Light-Induced Field Enhancement in Nanoscale Systems from First-Principles: The Case of Polyacenes

Using first-principles calculations we studied the electric field enhancement in polyacene molecules upon illumination. These molecules can be seen as a specific class of C-based (i.e., graphene-derived) nanostructures, recently proposed as alternative materials for plasmonics. We demonstrate that optical transitions may generate oscillating dipolar response charge, giving rise to an induced electric field near the molecule, which thus acts as a plasmon-like nanoantenna. While the field amplification in the vicinity of single acenes is rather small and decreases when the size of the system is increased, it may be selectively enhanced in the case of acenes assemblies. This paves the way for the design of more complex C-based architectures explicitly conceived to improve the amplification factor.