Hexacene on Cu(110) and Ag(110): Influence of the Substrate on Molecular Orientation and Interfacial Charge Transfer.
Marie S SätteleAndreas WindischbacherKatharina GreulichLarissa EggerAnja HaagsHans KirschnerRuslan OvsyannikovErika GiangrisostomiAlexander GottwaldMathias RichterSerguei SoubatchF Stefan TautzMichael G RamseyPeter PuschnigGeorg KollerHolger F BettingerThomas ChasséHeiko PeisertPublished in: The journal of physical chemistry. C, Nanomaterials and interfaces (2022)
Hexacene, composed of six linearly fused benzene rings, is an organic semiconductor material with superior electronic properties. The fundamental understanding of the electronic and chemical properties is prerequisite to any possible application in devices. We investigate the orientation and interface properties of highly ordered hexacene monolayers on Ag(110) and Cu(110) with X-ray photoemission spectroscopy (XPS), photoemission orbital tomography (POT), X-ray absorption spectroscopy (XAS), low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and density functional theory (DFT). We find pronounced differences in the structural arrangement of the molecules and the electronic properties at the metal/organic interfaces for the two substrates. While on Cu(110) the molecules adsorb with their long molecular axis parallel to the high symmetry substrate direction, on Ag(110), hexacene adsorbs in an azimuthally slightly rotated geometry with respect to the metal rows of the substrate. In both cases, molecular planes are oriented parallel to the substrate. A pronounced charge transfer from both substrates to different molecular states affects the effective charge of different C atoms of the molecule. Through analysis of experimental and theoretical data, we found out that on Ag(110) the LUMO of the molecule is occupied through charge transfer from the metal, whereas on Cu(110) even the LUMO+1 receives a charge. Interface dipoles are determined to a large extent by the push-back effect, which are also found to differ significantly between 6A /Ag(110) and 6A /Cu(110).
Keyphrases
- high resolution
- single molecule
- density functional theory
- quantum dots
- electron microscopy
- highly efficient
- aqueous solution
- visible light
- metal organic framework
- molecular dynamics
- molecular dynamics simulations
- magnetic resonance imaging
- optical coherence tomography
- amino acid
- solar cells
- structural basis
- high speed
- mass spectrometry
- high throughput
- ionic liquid
- room temperature
- crystal structure
- single cell
- data analysis