We fabricated ambipolar organic thin-film transistors (OTFTs) using C60 and pentacene. The electronic structure of the interface was investigated by using ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy. The magnitude of the interface dipole and the band bendings at the interface was determined, and the complete energy level diagram for C60 on pentacene (C60 /pentacene) was obtained. The lowered band offsets, due to the enhanced charge redistribution in C60 /pentacene relative to pentacene on C60, are favorable for the ambipolar OTFTs. The measured field-effect mobilities were 0.017 cm2 V s and 0.007 cm2 V s for the p -channel and the n -channel operations, respectively. The threshold voltages were -2 V for the p channel and 15.6 V for the n channel, comparable to those of unipolar OTFTs using C60 or pentacene.
Bibliographical noteFunding Information:
This work is supported by the BK21 project of the Korea Research Foundation (KRF) and the KOSEF through the National Core Research Center for Nanomedical Technology.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)