Self-Assembled Donor–Acceptor Trefoils: Long-Lived Charge Separated State through Aggregation

Organic photonic
nanostructures, capable of efficient light harvesting
and storage, provide new avenues in constructing solution processable
solar cells and photovoltaic devices. In this contribution, we demonstrate
ca. 104-fold enhancement in the photoinduced charge recombination
lifetime (τcra = 2.62 ns) in the aggregated
state of donor–acceptor (D–A) dyads and trefoils comprised
of triphenylamine and naphthalimide. The D–A dyads and trefoils
undergo self-assembly in THF forming spherical/vesicular aggregates
dictated by weak co-operative intermolecular interactions in contrast
to monomer in CH3CN. Observed long-lived charge transfer
intermediates in the aggregated state of triphenylamine-naphthalimide
(TN) based conjugates could be attributed to the delocalization of
photogenerated charge carriers through D–A stacks. D–A
supramolecular architectures thus emerged could serve as promising
scaffolds for light harvesting, molecular electronics and photofunctional
applications.