  Biology offers a boundless source of adaptation, innovation, and inspiration.
A wide range of photosynthetic organisms exist that are capable of harvesting
solar light in an exceptionally efficient way, using abundant and low-cost
materials. These natural light-harvesting complexes consist of proteins that
strongly bind a high density of chromophores to capture solar photons and
rapidly transfer the excitation energy to the photochemical reaction centre.
The amount of harvested light is also delicately tuned to the level of solar
radiation to maintain a constant energy throughput at the reaction centre and
avoid the accumulation of the products of charge separation. In this Review,
recent developments in the understanding of light harvesting by plants will be
discussed, based on results obtained from single molecule spectroscopy studies.
Three design principles of the main light-harvesting antenna of plants will be
highlighted: (a) fine, photoactive control over the intrinsic protein disorder
to efficiently use intrinsically available thermal energy dissipation
mechanisms; (b) the design of the protein microenvironment of a low-energy
chromophore dimer to control the amount of shade absorption; (c) the design of
the exciton manifold to ensure efficient funneling of the harvested light to
the terminal emitter cluster.
