The exciton couplings (H ab =J ab ) mediate the exciton transport process between the diabatic states (Eq. 2). The exciton transport rates are computed for the dimers with the centroid distances smaller than 10 Å, isolated from the optimised crystal structures. The J ab of isolated dimers were computed applying a diabatisation method based on the transition dipole moments of S 1 states of isolated molecules and S 1 and S 2 states of dimers, as implemented in the fromage code. This method takes into account the short-range (exchange, orbital overlap, charge-transfer) and long-range Coulomb interactions. Both reorganisation energies for the exciton transport and exciton couplings are computed based on the TD-ωB97XD/6-311+G(d,p) excited states.