▎ 摘　　要

Work function engineering of graphene facilitates its application as a transparent electrode material in organic electronic devices. Toward this end, we demonstrate the dependence of the work function of plasma-fluorinated epitaxial graphene on the polarity of carbon-fluorine bonds which is controlled by the nature of chemical bonding (ionic, semi-ionic, or covalent) between fluorine and carbon atoms. The work function of fluorinated graphene was measured using ultraviolet photoelectron spectroscopy and the polarity of carbon-fluorine bonds was established using x-ray photoelectron spectroscopy. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752443]