Observation of Hole States at Perylene/Au(110) and Au(111) Interfaces

Abstract

The geometric and electronic structures of the perylene monolayers on gold single-crystal surfaces and the effect of Br doping have been investigated. Perylene molecules adsorbed on the Au(110)(1 × 2) surface form a monolayer with the molecular long axis aligned along the [11̅0] direction and the molecular plane tilted at ±15° to the short axis, in contrast with the parallel molecular plane on the Au(111) surface. The orientation of the molecules is determined by the polarization dependence of the X-ray absorption fine structure spectroscopy near the carbon K-edge (C K NEXAFS). Angle-resolved photoemission spectroscopy shows a ″binary star″ pattern for the 2D momentum map of photoemission from the perylene highest occupied molecular orbital (HOMO) on the Au(110)(1 × 2) surface, which is consistent with the tilted molecular plane. The doped Br penetrates the perylene monolayer and causes a dramatic change in the orientation of the molecules. The perylene molecules are ionized because of the charge transfer promoted by the work function increase induced by the Br adsorbed on the gold surface. Cationic perylene shows resonance with the singly unoccupied molecular orbital (SUMO) in the C K NEXAFS spectra. This resonance can be a useful spectral fingerprint for tracing the hole created in organic semiconductors.

Peri-Tetracene from 1,1′-Bitetracene: Zipping up Structurally Defined Graphene Nanoribbons

“…This affects the wave vector k ||, which is a function of θ at constant kinetic energy E kin of the free photoelectrons . Choosing θ = 30°, regions with maximal HOMO intensities for related π-conjugated molecules are covered (cf., e.g., ref ). The enlarged view of the low-binding-energy region of angular integrated valence band spectra of a monolayer Bi4A on Cu(111) before and after annealing (Figure a) shows characteristic features, which we assigned with the help of calculations.…”

Influence of the Side Chain Structure on the Electronic Structure and Self-Organization Properties of Low Band Gap Polymers

“…As an example, for molecules deposited on clean metal surfaces prepared in ultrahigh vacuum, the introduction of a dielectric spacer layer may change a chemisorption-driven fractional charge transfer to an electrostatically driven integer charge transfer mechanism. , On the other hand, in most cases, studies on particular interfaces are not suited to validate the applicability of different models for the interface energetics at the huge variety of organic–substate interfaces. Here, we focus on the comparison of the energy level alignment of four polymers with different substitution patterns, and for a deeper discussion of the nature of the integer or fractional charge transfer levels, we refer to the literature (e.g., refs – ).…”

Planar BN-Doped Nanographenes on Reactive Metal Surfaces: A Promising Pathway for the Preparation of BN-Doped Graphene Layers

“…Moreover, also the choice of the metal substrate is important for a bottom-up synthesis via on-surface synthesis, even bimetallic templates were used . Depending on the surface reconstruction, especially on Au(110)-(1 × 2), the adsorption geometry of the molecules might be slightly tilted, which enables a maximal interaction of the molecule with the substrate, as recently shown for perylene . For a porphyrin on Au(111), bistable species with nondegenerate electronic energy levels were observed .…”

“…32 Depending on the surface reconstruction, especially on Au(110)-(1 × 2), the adsorption geometry of the molecules might be slightly tilted, which enables a maximal interaction of the molecule with the substrate, as recently shown for perylene. 33 For a porphyrin on Au(111), bistable species with nondegenerate electronic energy levels were observed. 34 As a consequence, the interaction strength is not necessarily equal for all atoms of the molecule, and thus local interactions may depend on the detailed adsorption geometry.…”