2 research outputs found
Microfluidic out-of-equilibrium control of molecular nanotubes
The bottom-up fabrication of functional nanosystems for light-harvesting applications and excitonic devices often relies on molecular self-assembly. Gaining access to the intermediate species involved in self-assembly would provide valuable insights into the pathways via which the final architecture has evolved, yet difficult to achieve due to their intrinsically short-lived nature. Here, we employ a lab-on-a-chip approach as a means to obtain in situ control of the structural complexity of an artificial light-harvesting complex: molecular double-walled nanotubes. Rapid and stable dissolution of the outer wall was realized via microfluidic mixing thereby rendering the thermodynamically unstable inner tubes accessible to spectroscopy. By measurement of the linear dichroism and time-resolved photoluminescence of both double-walled nanotubes and isolated inner tubes we show that the optical (excitonic) properties of the inner tube are remarkably robust to such drastic perturbation of the system's supramolecular structure as removal of the outer wall. The developed platform is readily extendable to a broad range of practical applications such as e.g. self-assembling systems and molecular photonics devices
Interplay between structural hierarchy and exciton diffusion in artificial light harvesting
Unravelling the nature of energy transport in multi-chromophoric
photosynthetic complexes is essential to extract valuable design blueprints for
light-harvesting applications. Long-range exciton transport in such systems is
facilitated by a combination of delocalized excitation wavefunctions (excitons)
and remarkable exciton diffusivities. The unambiguous identification of the
exciton transport, however, is intrinsically challenging due to the system's
sheer complexity. Here we address this challenge by employing a novel
spectroscopic lab-on-a-chip approach: A combination of ultrafast coherent
two-dimensional spectroscopy and microfluidics working in tandem with
theoretical modelling. This allowed us to unveil exciton transport throughout
the entire hierarchical supramolecular structure of a double-walled artificial
light-harvesting complex. We show that at low exciton densities, the outer
layer acts as an antenna that supplies excitons to the inner tube, while under
high excitation fluences it protects the inner tube from overburning. Our
findings shed light on the excitonic trajectories across different sub-units of
a multi-layered supramolecular structure and underpin the great potential of
artificial light-harvesting complexes for directional excitation energy
transport.Comment: Submitted to Nature Communications; main manuscript 37 pages (incl.
references) and 5 figures. SI 59 pages (incl. references) and 25 Figure