The development of more efficient photovoltaic and photosynthetic devices is a central challenge for solar energy utilization and a sustainable energy economy. A promising route towards higher energy efficiency is light harvesting. In nature, light harvesting is widely used by phototrophic organisms to increase overall conversion efficiencies and extend the spectral range of absorption energies. So far, most attempts to exploit light harvesting for systematic improvement of photocells and artificial photosynthetic devices have been elusive, because the underlying excitation energy transfer process between chromophores is poorly understood and thus hard to control. The goal of the proposed project is to achieve a detailed, molecular-level understanding of natural light harvesting.