Preparing fullerene derivatives, comprises reacting fullerene with at least one halogen atom in a reactor, where at least one additional chemical element is added to the reactor. Independent claims are also included for: (1) an organic semiconductor layer comprising the fullerene derivatives prepared by the above method; (2) a doped organic semiconductor layer comprising an organic hole-transporting semiconductor material and the fullerene derivative prepared by the above method; (3) an organic diode, organic photoactive component, preferably solar cell, photo detector or light emitting diode, which are constructed of several layers, where at least one of the layers comprises the fullerene derivative prepared by the above method; and (4) a battery comprising the fullerene derivative prepared by the above method.