Site-dependent charge transfer at the Pt(111)-ZnPc interface and the effect of iodine

Abstract

The electronic structure of ZnPc, from sub-monolayers to thick films, on bare and iodated Pt (111) is studied by means of X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy (STM). Our results suggest that at low coverage ZnPc lies almost parallel to the Pt(111) substrate, in a non-planar configuration induced by Zn-Pt attraction, leading to an inhomogeneous charge distribution within the molecule and charge transfer to the molecule. ZnPc does not form a complete monolayer on the Pt surface, due to a surfacemediated intermolecular repulsion. At higher coverage ZnPc adopts a tilted geometry, due to a reduced molecule-substrate interaction. Our photoemission results illustrate that ZnPc is practically decoupled from Pt, already from the second layer. Pre-deposition of iodine on Pt hinders the Zn-Pt attraction, leading to a non-distorted first layer ZnPc in contact with Pt (111), and a more homogeneous charge distribution and charge transfer at the interface. On increased ZnPc thickness iodine is dissolved in the organic film where it acts as an electron acceptor dopant.

On-surface manipulation of atom substitution between cobalt phthalocyanine and the Cu(111) substrate

“…In the case of 3 ML coverage, there is also a pronounced shoulder attributed to the relative shakeup satellites, which locate at 1.9 eV higher binding energy compared to the main peaks and are well consistent with other reports of metal phthalocyanine. 23,44,55 Secondly, the peak shape was preserved well for all spectra during annealing either at monolayer or multilayer. Similar to the case of N 1s spectra, there is a peak shi of 0.4 eV when annealed at 673 K for monolayer and less than 0.1 eV for multilayer with respect to the spectrum as deposited at RT, which again shall be attributed to the polarization screening effect from metal substrate due to desorption of macrocycle induced by thermal annealing.…”

A TbPc2 sub-monolayer deposit on a titanium dioxide ultrathin film: magnetic, morphological, and chemical insights

“…16,35,45 This is at variance with previous findings for TbPc 2 or phthalocyanine molecules in direct contact with a bulk TiO 2 substrate where oxidation of the molecular species was observed. [31][32][33][34][35] Such difference in the substrate reactivity could be an indication of the absence of catalytic sites characteristic of many TiO 2 surfaces, such as oxygen vacancies, 30,31 or it can be attributed to a different intrinsic reactivity of the TiO 2 lepidocrocite structure compared to the rutile phase used in our previous investigation. 35,46 We notice that also the Ti2p and O1s spectra collected after the TbPc 2 deposition (Figure 1a and Figure S1, bottom panels) do not reveal significant variations in both the line shape and the semiquantitative analysis (Table S1), thus confirming the innocent role played by the TiO 2 layer on the assembled molecules.…”

“…30,31 In particular, the deposition of metallated phthalocyanines (MPc) systems on a bulk TiO 2 substrate showed that molecules in direct contact with the surface interact strongly and can undergo an oxidation process. [31][32][33][34] Furthermore, our recent studies on bulk TiO 2 single crystals revealed that also the sub-monolayer of TbPc 2 molecules deposited on the TiO 2 (110) rutile surface undergo a strong interfacial interaction independently on the surface preparation and the presence of surface defects. 35 In this work, we studied the molecular organization and the magnetic properties of a sub-monolayer of TbPc 2 molecules thermally sublimated on a TiO 2 film grown with a lepidocrocite-like structure on Ag(100) (TiO 2 -L).…”

Theoretical Insights into Unexpected Molecular Core Level Shifts: Chemical and Surface Effects

“…MPc-s are planar organometallic molecules containing eight N atoms: four aza nitrogens (N–, marked in blue in Figure a), and four iminic nitrogens coordinated to the metal core (metal–N, in red in Figure a). Despite their nonequivalence, it is well-known that the 1s core levels of the two types of N atoms lie very close in energy (e.g., ∼ 0.3 eV for CuPc), which normally leads to the observation of an unresolved single N 1s core level peak in photoemission experiments. , However, unexpected features are frequently found in the N 1s energy region. This is the case, for example, of some MPc molecules deposited on Cu(110).…”

“…Despite their nonequivalence, it is well-known that the 1s core levels of the two types of N atoms lie very close in energy (e.g., ∼ 0.3 eV for CuPc 30 ), which normally leads to the observation of an unresolved single N 1s core level peak in photoemission experiments. 31,32 However, unexpected features are frequently found in the N 1s energy region. This is the case, for example, of some MPc molecules deposited on Cu(110).…”