Adsorption of pentacene on filled d-band metal surfaces: Long-range ordering and adsorption energy

Abstract

The growth of pentacene on suitable metallic templates is studied by means of low-energy electron diffraction and ultraviolet photoelectron spectroscopy. Highly ordered pentacene single layers can be prepared by deposition on filled d-band metal templates kept at 370 K. The presence of the steps for the Cu(119) vicinal surface and of the Au troughs for the Au(110)-(1 x 2) surface allows the formation of commensurate long-range ordered structures with (3 x 7) and (3 x 6) periodicities, respectively. A detailed analysis of the molecular induced electronic states evolution is performed for different growth morphologies. The adsorption energy of the ordered molecular single layers on the Au(110) surface is lower (1.90 eV) than on the Cu vicinal surface (2.36 eV), where the steps enhance the molecule adsorption energy.

Interpretation of valence band photoemission spectra at organic-metal interfaces

“…Still several UPS and ARPES studies have reported on the formation of interacting and hybrid states at the organic/noble-metal interface within the substrate d-band region. 12,[16][17][18][19][20][21][22][23][24][25][26][27][28][29] In these studies intense and sharp photoemission features were found upon the adsorption of large (M-Pc, pentacene) and smaller (anthracene, small thiols, adenine) organic molecules. Ab initio calculations and polarization dependent and angular-resolved measurements were also reported generally highlighting the interface character of the photoemission features.…”

“…14,15 Despite this difficulty several studies reported on the formation of hybrid molecule-substrate interface states within the single-crystal substrates d-band BE region. 12,[16][17][18][19][20][21][22][23][24][25][26][27][28][29] The present paper focuses on the substrate contribution in the EDC of the adsorbed system and it highlights the importance of the interface scattering when interpreting the EDC of a thin layer of large, π -conjugated organic molecules on noble-metal single-crystal substrates. As will be shown in the following, the adsorption promotes the measurements of EDCs in photoemission that are reminiscent of the metal three-dimensional (3D)-integrated DOS, i.e., EDCs that mimic polycrystalline metal surfaces.…”

Molecular charge distribution and dispersion of electronic states in the contact layer between pentacene and Cu(119) and beyond

“…The rationale of this choice of substrate is to obtain an aligned film with pentacene lying flat on the surface and oriented along the Cu͑119͒ steps. [9][10][11][12] Extended regions of the substrate with uniform steps and terraces were obtained after several cycles of ion sputtering ͑Ar + , E = 600 eV͒ and annealing at 740 K, which are followed by slow cooling to room temperature ͑RT͒. The copper surface quality was checked by both STM and low-energy electron diffraction.…”

“…The copper surface quality was checked by both STM and low-energy electron diffraction. 9 Pentacene was deposited in situ by evaporating pentacene from a resistively heated quartz crucible at a rate of ϳ0.1 nm/ min in a residual pressure always Ͻ5 ϫ 10 −10 mbar. During the deposition, the substrate was kept either at 370 K to limit the adsorption to a single layer 8 or at RT for a higher coverage.…”

Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

“…12 This metallic surface is widely used as a template a) lorenzo.massimi@uniroma1.it b) carlo.mariani@uniroma1.it to follow a bottom-up approach in the formation of highly ordered molecular films, thanks to the twofold missing-row reconstruction along the [001] direction, that can drive the formation of one-dimensional (1D) molecular chains. 13,14 MPc adsorption on Au(110)-(1×2) leads to the formation of ordered chains along the [110] direction, with the MPc molecular plane oriented parallel to the surface. 15,16 The planar orientation, in particular for the first single-layer (SL), is due to an interaction between the metal-phthalocyanine orbitals and the Au electronic levels.…”