In Situ Analysis of Hole Injection Barrier of O2 Plasma-Treated Au with Pentacene Using Photoemission Spectroscopy

Pentacene was in situ deposited on both bare-Au and O2 plasma-treated Au (O2-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 5.28eV as the Au surface was treated with O2 plasma. The corresponding interface dipoles were -0.30eV for bare Au and -0.71eV for O2-Au, respectively. Thus the hole injection barrier at the interface reduced from 0.45 to 0.15eV by the O2 plasma before the deposition of pentacene, leading to an increase of the linear field-effect mobility of thin-film transistors.