Ambipolar operation of fullerene field-effect transistors by semiconductor/metal interface modification

We report an ambipolar operation in field-effect transistors of C-60 and metallofullerene Dy @ C-82 by modification of semiconductor/metal electrode interface with perfluoroalkylsilane (FAS) molecules. Kelvin probe experiments revealed that the work function of the gold surface modified with FAS molecules increased by 0.55 eV as compared to the untreated gold. Hole injection into fullerenes is qualitatively understood in terms of this work-function change induced by the FAS molecules. The present results indicate that the charge injection from electrodes to organic semiconductors can be controlled simply by modification of semiconductor/metal interface without changing materials themselves. (c) 2005 American Institute of Physics.