The reason for the Poole-Frenkel (PF) mobility field dependence in dependence in disordered organic materials is believed to be a long range spatial correlation in the distribution of enough levels of transport sites. This correlation is produced by molecules with significant permanent dipole moments. However, experimental data offer a strong evidence that in transport layers containing no molecules with high dipole moment essentially the same PF dependence of transport parameters on the mean intersite separation. By means of computer simulation and analytic calculation we consider the influence of deep traps on the charge carrier mobility in organic materials.