Adsorption geometry of tetracene on SiO2/Si (1 1 1) substrate with the balance of molecule–substrate and intermolecular interaction

The growth of tetracene on SiO2/Si(1 1 1) substrate has been studied by ultraviolet photoemission spectroscopy measurements. Seven emission features of the organic material are located at 2.26, 3.56, 4.77, 5.88, 6.98, 8.18 and 9.90 eV, respectively, below the Fermi level. The changes in binding energy and work function during the deposition of tetracene molecules on SiO2 substrate indicate an interaction between tetracene molecule and substrate. The interaction between tetracene molecule and substrate is weaker than that between the organic and silicon substrate. The reduction in work function is due to the formation of interface dipole. Based on the density functional theory (DFT) calculation, tetracene molecules are arranged in an upright standing manner with the optimal growth of a small cluster consisting four molecules.