Characteristics of Cyclic Triarylamine Hexamers and Application to Organic Field Effect Transistor

Cyclic hexamers consisting of a 4-octyl, 4-octyloxy and 4-(2-ethylhexyloxy)triphenylamine unit were synthesized via a Buchwald-Hartwig cross coupling reaction using A-A, and B-B type monomers in order to avoid the formation of other cyclic oligomers such as a pentamer and a heptamer. Unlike different size of cyclic oligomers, all hexamers we examined showed clear cold crystallization in 165-240°C in the DSC thermograms. Resulting oligomers were characterized and applied to hole transporting active layer in an organic field effect transistor. The hexamer with 4-octyl groups exhibited the highest field effect hole mobility (1.99 ×10-3 cm2 V-1s-1).