  We present a novel, counter-intuitive method, based on dark state protection,
for significantly improving exciton transport efficiency through `wires'
comprising a chain of molecular sites with an intrinsic energy gradient.
Specifically, by introducing `barriers' to the energy landscape at regular
intervals along the transport path, we find that undesirable radiative
recombination processes are suppressed due to a clear separation of sub-radiant
and super-radiant eigenstates in the system. This, in turn, can lead to an
improvement in transmitted power by many orders of magnitude, even for very
long chains. From there, we analyse the robustness of this phenomenon to
changes in both system and environment properties to show that this effect can
be beneficial over a range of different thermal and optical environment
regimes. Finally, we show that the novel energy landscape presented here may
provide a useful foundation for overcoming the short length scales over which
exciton diffusion typically occurs in organic photo-voltaics and other
nanoscale transport scenarios, thus leading to considerable potential
improvements in the efficiency of such devices.
