is much less, because the various concentration dependences mostly cancel each other out. An exemplary embodiment of the invention is a computer implemented method of performing transport simulation of a disordered semiconductor device. The basic steps of the method are receiving an input specihcation of composition and geome try of the disordered semiconductor device, performing a three-dimensional master equation simulation of electron and hole transport and recombination based on the input specihcation, and providing simulated transport results of the disordered sem i conductor device as an output. As indicated above, the three-dimensional master equation simulation has the features of: 1) charge transport is modeled as incoher ent hopping between localized molecular states; 2 ) recombination is modeled as a nearest-neighbor process where an electron at a hrst location and a hole at a second location can recombine at either the hrst location or the second location (here the hrst location and the second location are any two nearest neighbors in a set of the localized molecular states), 3) the rate of the recombination is modeled as a product of a prefactor , hopping rates and state occupancies, and 4) the prefactor 7 is given by an empirically derived analytic expression. Signihcant advantages are provided. The method enables carrying out simula tions under conditions (e.g., low voltage) for which no KMC simulations are possible, and / or with much less simulation time. The approach is versatile, with no signihcant limitations on the device geometries that can be modeled. It can be easily applied for various technical uses such as in processes for stack development in any type of device structure. Relevant included physics includes charge transport and light generation and the simulation domain ranges from nanometers to micrometers. The main technical effect provided by this work is accurate simulation results in disor dered semiconductor devices with significantly less simulation time than would be required by conventional simulation approaches. For example, the present approach is, at low voltages, orders of magnitude faster than 3D-KMC simulations, and still incorporates t o a good degree of accuracy the effects of the molecular randomness on the non-uniform current density and recombination rate. The present approach has numerous applications. Any kind of disordered semicon ductor device can be simulated, including but not limited to: Organic Light-emitting Diodes (OLEDs), thin him organic solar cells, organic semiconducting multilayer sys-