Organic materials employed to harvest light consist of multiple chromophoric building blocks which are arranged in a three-dimensional structure. Their propensity to absorb light as well as their functionality to transform photons into chemical energy is given by both the optoelectronic properties of the monomers and the interchromophore structure. In this thesis, time-resolved laser spectroscopy from the infra-red to UV and fs to μs timescales is applied to decipher the structure-property relationships in multichromophoric systems. In addition, the experimental upgrade and development of two transient absorption instruments is described, which increases the spectral window from 360-720 to 330-1600 nm. First, the photophysics of the monomeric building blocks are established, comprising naphthalenediimide, perylene and pentacene chromophores. In a second step, two or more of these building blocks are covalently linked in supramolecular systems to study charge separation and singlet fission as a function of interchromophore geometry.