Rational development of organic electronic devices requires a molecular insight into the structure-performance relationships that can be established for the organic active layers. However, the current molecular-scale simulations of these devices are limited to nanometer sizes, well below the micrometer-sized systems that are needed in order to consider actual-scale morphologies and to reliably model low dopant concentrations and trap densities. Here, by enabling descriptions of both the short-range and the long-range electrostatic interactions in master equation simulations, it is demonstrated that reliable molecular-scale simulations can be applied to systems 100 times larger than those previously accessible. This quantum leap in the modeling capability allows us to uncover large inhomogeneities in the charge-carrier distributions. Furthermore, in the case of a blend morphology, charge transport in an actual-scale device is found to behave differently as a function of applied voltage, compared to the case of a uniform film. By including these features in realistic-scale descriptions, this methodology represents a major step into a deeper understanding of the operation of organic electronic devices.
