Kinetic Monte Carlo (KMC) simulations model exciton diffusion as a sequence of hops between molecules in the crystal. In this work, KMC simulations were performed using the first reaction method. In this method, the simulation proceeds by iteration of the following steps. In the first step, an exciton is placed on a molecule i in the crystal (determined by the previous step). In the second step, the rate constants between molecule i and its neighbors are calculated. In this work, rate constants were calculated using the Marcus expression: