Adapting the Forster theory of energy transfer for modeling dynamics in aggregated molecular assemblies

The remarkable efficiencies of solar energy conversion attained by photosyn thetic organisms derive partly from the designs of the light-harvesting app aratuses. The strategy employed by nature is to capture sunlight over a wid e spectral and spatial cross section in chromophore arrays, then funnel the energy to a trap (reaction center). Nature's blueprint has inspired the co nception of a diversity of artificial light-harvesting antenna systems for applications in solar energy conversion or photonics. Despite numerous, wid e-ranging studies, truly quantitative predictions for such multichromophori c assemblies are scarce because Forster theory in its standard form often s eems to fail. We report here a new framework within which energy transfer i n molecular assemblies can be modeled quantitatively using a generalization of Forster's theory. Our results show that the principles involved in opti mization of energy transfer in confined molecular assemblies are not reveal ed in a simple way by the absorption and emission spectra because such spec tra are insensitive to length scales on the order of molecular dimensions.