Our simulations reveal ultrafast exciton localization with characteristic time constants of about 20 fs for the models with a = 5.5 Å, ∼40 fs for free tetramer with a = 3.5 Å, and ∼100 fs for SAM with a = 3.5 Å. The exciton localization times are much shorter than the corresponding ππ * lifetimes, which are on a ps timescale at the used level of theory. During excited state dynamics the ππ * states undergo a stronger localization for longer intermolecular distances (a = 5.5 Å) than for the shorter ones (a = 3.5 Å). Moreover, we observe exciton transfer between azobenzene monomers while dynamics proceed in the ππ * manifold. The nπ * excitons are mostly completely localized (on a single monomer). And once the nπ * exciton is localized on a particular monomer, it is usually trapped there, whereas exciton transfer to another monomer is a rare event (observed only for four trajectories, in case of models with a = 3.5 Å).