Metal-organic interface functionalization via acceptor end groups: PTCDI on coinage metals

Abstract

We present a comprehensive study of the complex interface between perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) and the (111) surfaces of the three coinage metals. The specific structural, electronic, and chemical properties of the interface rendered by the different substrate reactivities are monitored with low-energy electron diffraction (LEED), x-ray standing waves (XSW), and ultraviolet and x-ray photelectron spectroscopy (UPS and XPS). In particular, the balance between molecule-substrate and molecule-molecule interactions is considered when interpreting the core-level spectra of the different interfaces. By presenting additional adsorption distances of the unsubstituted perylene, we showthat the molecular functionalization via end groups with acceptor character facilitates the charge transfer from the substrate but it is not directly responsible for the associated short adsorption distances, demonstrating that this frequently assumed correlation is not necessarily correct

Orientation-Dependent Work-Function Modification Using Substituted Pyrene-Based Acceptors

“…All three features show their maximum intensity between 3 and 6 Å coverage, which indicates that they originate from molecules in the interfacial region. The occurrence of the new peaks is reminiscent of what was observed for related acceptors on metal surfaces, e.g., F4-TCNQ, 12 HATCN, 59 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA), 17 , 60 perylene-3,4,9,10-tetracarboxylic diimide, 61 6,13-pentacenequinone (P2O), 5,7,12,14-pentacenetetrone (P4O), 16 and diindenoperylene (DIP), 62 , 63 where substantial negative charge is transferred from the substrate to the molecule upon chemisorption. In analogy, we assign the feature close to the Fermi level to hybrid orbital(s) formed by metal states and the molecular LUMO now being partially filled.…”

Photoelectron spectroscopy studies of PTCDI on Ag/Si(111)-3×3

“…3d) involves two main features, the strongest of which sits at a BE position of about 285.0 eV while the smaller one is located at 288.5 eV. The larger and smaller features have previously been assigned to carbons from the perylene core and the imide endgroup, respectively [4]. The spectrum also contains a number of shakeups on the higher BE side of the main feature.…”

“…The 5.0 ML spectrum can be fitted with seven components labeled as a-g. The perylene related feature was fitted using three components a-c as in previous work [4,7,17], where a corresponds to C-H (C1 and C2 in Fig. 1), b to C-C (C3, C5 and C6) and c to C-C=O (C4).…”

“…1 where different carbon atoms have been numbered as C1-C7 for later convenience. The electronic structure of thin PTCDI films has previosuly been studied using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) on Si(111) [2], Ni(111) [2], Au(111) [3,4], Ag(111) [4], Cu (111) [4], TiO 2 [5,6] and Ag/Si(111)-× 3…”

Resolving intramolecular-distortion changes induced by the partial fluorination of pentacene adsorbed on Cu(111)

“…Substrate-induced molecular distortions are important to properly account for the interface dipole between a metal electrode and an organic active material [1,2]. They usually involve functional groups with heteroatoms that act as the main channel whereby the electronic and/or chemical coupling with the surface atoms occurs [3][4][5][6]. However, the distortion of a hydrocarbon core has not been experimentally probed with the same success [7,8] and, in most cases, it has only been accessible through state-of-the-art density-functionaltheory (DFT) calculations [8][9][10].…”