High performance n-type organic field-effect transistors based on halogenated derivatives of naphthalene tetracarboxylic diimides

We synthesized three kinds of naphthalene tetracarboxylic diimides (NDIs) containing halogenated phenyl groups by one-step reaction, and they were used as organic semiconductor layers in top-contact Organic field-effect transistors (OFETs). Besides, we adopted SiO2/Si substrates that treated by N-octadecylphosphonic acid (ODPA). In addition, a layer of 4, 4', 4"-triphenylamine (n-3-methylphenyl-n-phenylamine) triphenylamine (m-MTDATA) was deposited by vacuum between the organic semiconductor layer and the gold electrode as the modification material. It was found through experiments that all the organic materials synthesized by us showed n-type organic semiconductor characteristics. Happily, the device made of NDI-FAN attained the highest electron mobility of 2.2 x 10(-1) cm(2)v(-1)s(-1) at room temperature and in air. The crystallinity and morphology of the films were characterized by x-ray diffraction (XRD) and atomic force microscope (AFM). The results expose that introducing electron withdrawing substituents into naphthalene tetracarboxylic diimides besides inserting ODPA and m-MTDATA are effective ways to achieve high electron mobility.