Performance improvement of a pentacene organic field-effect transistor through a DNA interlayer

Organic field-effect transistors (OFETs) with a top-contact structure were fabricated by applying deoxyribonucleic acid (DNA) as a hole injection layer using a simple spray-coating process. Compared with that of the bare OFET, the OFETs incorporated with a DNA hole injection layer exhibited a remarkable enhancement of field-effect mobility from 0.02 to 0.104 cm(2) V-1 s(-1). By analysing the electrical characteristics of OFETs and the surface morphology of pentacene film, the results showed that the dipole formation effect of the DNA interlayer effectively reduced the contact resistance between gold electrodes and pentacene. Consequently, improved hole injection was obtained along with enhanced electrical characteristics. This effect was also observed in OFETs based on an alpha-hexathiophene organic semiconductor and OFETs based on silver electrodes. In addition, a guanine base-pair, a major constituent of DNA, was selected to be further analysed and confirmed the existence of the dipole formation effect.