Evolution of interface properties of the Pentacene/Bi(0001) system

Using angle-resolved photoemission spectroscopy we measured the evolution of the electronic properties of the Pentacene (Pn)/Bi(0001) interface. From thickness dependent photoemission spectra of the substrate and Pn film we conclude that Pn growth is epitaxial. Pentacene highest occupied molecular orbital (HOMO) valence band features are identical for sub-monolayer (ML) as well as for thick films which suggests a thickness independent film morphology. The Pn/Bi interaction is weak and results in a lowering of the HOMO binding energy by 180 ± 5 meV and 80 ± 5 meV for the first and second MLs respectively. The interface dipole (ID) is fully developed over the first ～ 1.2 ML of Pn coverage and has a value of ID = 310 ± 10 meV. The hole injection barrier across the interface is Φ_h = 1.03 ± 0.01 eV.