Controlling
excitonic energy transfer at the molecular level is
a key requirement for transitioning nanophotonics research to viable
devices with the main inspiration coming from biological light-harvesting
antennas that collect and direct light energy with near-unity efficiency
using Förster resonance energy transfer (FRET). Among putative
FRET processes, point-to-plane FRET between donors and acceptors arrayed
in two-dimensional sheets is predicted to be particularly efficient
with a theoretical 1/r
4 energy transfer
distance (r) dependency versus the
1/r
6 dependency seen for a single donor–acceptor
interaction. However, quantitative validation has been confounded
by a lack of robust experimental approaches that can rigidly place
dyes in the required nanoscale arrangements. To create such assemblies,
we utilize a DNA brick scaffold, referred to as a DNA block, which
incorporates up to five two-dimensional planes with each displaying
from 1 to 12 copies of five different donor, acceptor, or intermediary
relay dyes. Nanostructure characterization along with steady-state
and time-resolved spectroscopic data were combined with molecular
dynamics modeling and detailed numerical simulations to compare the
energy transfer efficiencies observed in the experimental DNA block
assemblies to theoretical expectations. Overall, we demonstrate clear
signatures of sheet regime FRET, and from this we provide a better
understanding of what is needed to realize the benefits of such energy
transfer in artificial dye networks along with FRET-based sensing
and imaging.