Hole mobility enhancement of pentacene organic field-effect transistors using 4,4′,4″-tris[3-methylphenyl(phenyl)amino] triphenylamine as a hole injection interlayer

Organic field-effect transistors (OFETs) were prepared and analyzed by inserting various thickness of 4,4′,4″-tris[3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA) between pentacene and gold electrodes as a hole injection layer. These OFETs showed a significant enhancement of hole mobility comparing to the corresponding single layer device. The interfacial morphologies of pentacene and pentacene/m-MTDATA contact were characterized by atomic force microscopy. The hole mobility improvement of OFETs was attributed to an intermediate energy level formed between pentacene and gold heterojunction when inserting an ultrathin m-MTDATA layer, leading to a remarkable reduction of contact resistance at the metal-organic interface.