The precise control of the doping characteristics of graphene-based systems is a key parameter for successful integration in devices and applications. Doping can tune graphene’s carrier density, which is important for the optimization of graphene-based flexible and transparent electrodes. Moreover, if doping is confined within one out of the two equivalent graphene sublattices, considerable band gaps can open that could serve for switching devices on and off. We use the density functional theory to explore the conditions of sublattice symmetry breaking in nitrogen-doped graphene. We show that the nucleation of graphene grains and their growth through the propagation of unpassivated zigzag edges could give rise to a highly unbalanced doping, due to exothermic substitutions on edge sites. Based on our ab initio results, we calibrate an event-driven kinetic Monte Carlo model that simulates the growth …