New semiconductors based on triphenylamine with macrocyclic architecture: synthesis, properties and applications in OFETs

Abstract

Two novel macrocycles based on triphenylamine (TPA) have been synthesized by McMurry coupling reactions. The cyclic compound 2 consisted of two triphenylamines linked with ethylene bridges bearing two n-butyl chains. The compound 3 was based on N,N,N′,N′-tetraphenylbenzidine (TPD) units with macrocyclic architecture. They were fully characterized by cyclic voltammetry, UV-vis absorption and self-assembly properties. The crystal structure of 2 was determined by X-ray analysis. Atomic force microscope and scanning electron microscope images showed that compound 3 could form interesting fiber-like nanostructures by self-assembly. Both of the compounds can be used as active layers for p-type OFETs. The OFET device based on 2 prepared via a vacuum-deposit method gave a mobility of 2.3 × 10^–3 cm² V^–1 s^–1 and a current on/off ratio of 10⁵. High quality thin films of 3 were fabricated by spin coating from solution, and gave a mobility of 2.0 × 10^–3 cm² V^–1 s^–1 with a current on/off ratio of 2 × 10⁵. The results showed that the TPA derivatives with cyclic structures might fit better for OFETs. They may provide promising new choices for organic semiconductors.