Electronic structure of perylene on Au studied by ultraviolet photoelectron spectroscopy and density functional theory

The electronic structure of perylene was analyzed by using ultraviolet photoelectron spectroscopy to introduce the energy level alignment of perylene/Au interface. The energy level alignment was studied by the onset of the highest occupied molecular orbital level and the shift of the vacuum level of the perylene layer, which was deposited on Au surface by stages. The measured onset of the highest occupied molecular orbital energy level was 1.0 eV from the Fermi level of Au, and the vacuum level was shifted 0.2 eV toward higher binding energy side with additional perylene layer. Furthermore, the density functional theory calculation was performed to identify the valence band spectrum of perylene film. The good agreement between the experimental and theoretical valence band spectrum allows us to assign each peak of the valence band spectrum, which was obtained from the perylene/Au film. The representative molecular orbital shapes, which composed the valence band of perylene, are presented in this report.