Similarities and Differences in the Optical Response of Perylene-Based Hetero-Bichromophores and Their Monomeric Units

The linear and nonlinear optical response of molecular hetero-dimers and their composing perylene units is explored with fluorometry, steady-state and transient absorption, and coherent two-dimensional electronic spectroscopy. Supported by a Förster theory approach and ab initio calculations, we disclose the photoinduced dynamics comprising excitonic coupling, conformational changes, charge transfer, and relaxation dynamics. The influence of the actual orientation of the two chromophore units on these processes is investigated by employing two bichromophores built of the same monomeric units but linked differently.