Initial growth of N,N′-Bis(1-ethylpropyl)perylene-3,4,9,10-tetracarboxdiimide films on Cu (100)

J.C. MORENO-LÓPEZ, O. GRIZZI, M.L. MARTIARENA AND E.A. SÁNCHEZ

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 117 p. 11679 - 11685

1932-7447

We have studied the initial stages of the adsorption of N,N’-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxdiimide (EP-PTCDI) on Cu(100) using scanning tunnelling microscopy (STM), X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and density functional theory (DFT) calculations. STM images show that the EP-PTCDI molecules initially absorb on the surface forming ordered islands, without preferential nucleation in the step-edges of the terraces as is the case for adsorption of the same molecule on Ag. The 2D islands grow upon the completion of the surface with a single molecular layer. The experimental and simulated LEED patterns show that the molecular arrangement within the islands can be explained by a commensurate superstructure (3,4,2,6) and its four rotational equivalents. The electron spectroscopies shows net charge transfer from the surface to the molecule, and a decrease of about 0.7 eV in the work function after a single layer adsorption. The DFT calculations for the adsorption of a single layer qualitatively reproduce the features observed in STM images, and allow us to explain the observed charge exchange behaviour together with the work function change.