The results obtained demonstrate the applicability of nonlinear percolation theory for the description of charge-transfer processes in thin films of organic semiconductors, with the model object being a polycrystal with a system of intercrystalline barriers with large dispersion in heights. It was shown that the appearance of non-linear phenomena in electrophysical properties of such samples (long-time current relaxations, nonlinear VAC) is caused by changing of barrier heights distribution under the influence of external electric field on the filling of structural (defects) or impurity (adsorbed O-2) states.