High-mobility and low turn-on voltage n-channel OTFTs based on a solution-processable derivative of naphthalene bisimide

In organic electronics solution-processable n-channel field-effect transistors (FETs) matching the parameters of the best p-channel FETs are needed. Progress toward the fabrication of such devices is strongly impeded by a limited number of suitable organic semiconductors as well as by the lack of processing techniques that enable strict control of the supramolecular organization in the deposited layer. Here, the use of N,N'-bis(4-n-butylphenyl)- 1,4,5,8-naphthalenetetracarboxylic-1,4:5,8-bisimide (NBI-4-n-BuPh) for fabrication of n-channel FETs is described. The unidirectionally oriented crystalline layers of NBI-4-n-BuPh are obtained by the zone-casting method under ambient conditions. Due to the bottom-contact, top-gate configuration used, the gate dielectric, Parylene C, also acts as a protective layer. This, together with a sufficiently low LUMO level of NBI-4-n-BuPh allows the fabrication and operation of these novel n-channel transistors under ambient conditions. The high order of the NBI-4-n-BuPh molecules in the zone-cast layer and high purity of the gate dielectric yield good performance of the transistors.