Doping has been proved to be one of the powerful technologies to achieve significant improvement in organic electronic device performance. Herein, we systematically map out the interface properties of solution processed air stable n-type 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl (DMBI) doping fullerenes and fullerene derivatives, and establish an universal energy level alignment scheme for this class of n-doped system. At low doping levels where the charge transfer doping induces mainly bound charges, the energy level alignment of the n-doping organic semiconductor can be described by combining integer charger transfer (ICT)-induced shifts with a so-called double dipole step. At high doping levels significant density of free charges are generated and charge flows between the organic film and the conducting electrodes equilibrating the Fermi level in a classic "depletion layer" scheme. Moreover, we demonstrate that the model holds for both n and p-doping of π-backbone molecules and polymers. With the results, we provide the wide guidance for identifying application of current organic n-type doping technology in organic electronics.