In Situ Analysis of Hole Injection Barrier of O[sub 2] Plasma-Treated Au with Pentacene Using Photoemission Spectroscopy

Pentacene was in situ deposited on both bare-Au and O-2 plasma-treated Au (O-2-Au). The band structure at the interface of Au with pentacene was quantitatively determined using ultraviolet photoelectron spectroscopy. The work function of Au increased from 4.65 to 5.28 eV as the Au surface was treated with O-2 plasma. The corresponding interface dipoles were -0.30 eV for bare Au and -0.71 eV for O-2-Au, respectively. Thus the hole injection barrier at the interface reduced from 0.45 to 0.15 eV by the O-2 plasma before the deposition of pentacene, leading to an increase of the linear field-effect mobility of thin-film transistors. (c) 2007 The Electrochemical Society.