Pirrotta Alessandro, Solomon Gemma C, Franco Ignacio, Troisi Alessandro
Nano-Science Center and Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø, Denmark.
Department of Chemistry, University of Rochester , Rochester, New York 14627-0216, United States.
J Phys Chem Lett. 2017 Sep 21;8(18):4326-4332. doi: 10.1021/acs.jpclett.7b01828. Epub 2017 Aug 30.
Understanding energy transfer is of vital importance in a diverse range of applications from biological systems to photovoltaics. The ability to tune excitonic coupling in any of these systems, however, is generally limited. In this work, we have simulated a new class of single-molecule spectroscopy in which force microscopy is used to control the excitonic coupling between chromophores. Here we demonstrate that the excitonic coupling can be controlled by mechanical manipulation of the molecule (perylenediimide dimers and terrylenediimide-perylenediimide heterodimers) and can be tuned over a broad range of values (0.02-0.15 eV) that correspond to different regimes of exciton dynamics going from the folded to the elongated structure of the dimer. In all of the systems considered here, the switching from high to low coupling takes place simultaneously with the mechanical deformation detected by a strong increase and subsequent decay of the force. These simulations suggest that single-molecule force spectroscopy can be used to understand and eventually aid the design of excitonic devices.
