Highly ordered growth of PTCDA on epitaxial bilayer graphene

Meißner, Matthias; Gruenewald, Marco; Helgert, Christian; Udhardt, Christian; Forker, Roman; Fritz, Torsten

doi:10.1016/j.susc.2012.07.016

Cited by 26 publications

(24 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aggregation effects therefore remain to be discussed. In fact, the film structures of PTCDA monolayers (and in some cases also multilayers) on Au(111) [64,65], Au(100) [64], Ag(111) [44], and graphene or graphite [25,66]a r e well known. Additionally, the film structure of PTCDA on h-BN/Pt(111) is elucidated in Figs.…”

Section: Discussionmentioning

confidence: 99%

“…R(E,0) denotes the reflectance of the bare substrate at photon energy E, while R(E,d) is the reflectance recorded during film growth at a nominal adsorbate thickness d.T h e setup has been detailed previously [21,33]. For the spectral analysis the following substrates are used: h-BN/Rh(111) (this work), h-BN/Pt(111) (this work), Au(111) [22], Au(100) [23], Ag(111) [24], and bilayer graphene on 6H -SiC(0001) [25]. On graphene and h-BN the electronic coupling of the first PTCDA ML to the respective substrate is rather weak, as evidenced by an absorption behavior reminiscent of dissolved molecules [34][35][36].…”

Section: Methodsmentioning

confidence: 99%

“…STM images (not shown) of various samples were found to be consistent with this film thickness calibration. A similar procedure was carried out for graphene [25] and h-BN (this work), except that an electronically coupled PTCDA wetting layer is absent on these substrates.…”

Section: Methodsmentioning

confidence: 99%

“…(1)] to assess the optical absorption behavior of PTCDA films adsorbed on sp 2 -bonded layers, such as graphene on silicon carbide and metals covered by a hexagonal boron nitride (h-BN) or by a passivating molecular monolayer. For this purpose, measurements of PTCDA on h-BN/Rh(111) and h-BN/Pt(111) are compared to previous studies on various other substrates [22][23][24][25]. Surprisingly, only two distinct sets of S 0 → S 1 transition energies (hereafter called PTCDA HE and PTCDA LE for high and low energy, respectively) are observed, although the dielectric properties of the substrates vary considerably.…”

Section: Introductionmentioning

confidence: 96%

See 3 more Smart Citations

Optical transition energies of isolated molecular monomers and weakly interacting two-dimensional aggregates

et al. 2016

Self Cite

View full text Add to dashboard Cite

The optical excitation energies of organic dye molecules are often said to depend sensitively on the polarizability of the utilized substrate. To this end, we employ differential reflectance spectroscopy (DRS) to analyze the S 0 → S 1 fundamental transition energies observed for 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) as a function of coverage on various surfaces, such as sp 2-bonded insulating layers [graphene and hexagonal boron nitride (h-BN)], and noble metals pre-covered by a molecular wetting layer which prevents hybridization of the second-layer molecules with the metal states. We elucidate the optical absorbance behavior of PTCDA layers grown on h-BN/Rh(111) and on h-BN/Pt(111) and characterize their structures by means of scanning tunneling microscopy. Surprisingly, although the dielectric properties of the employed substrates differ substantially, only two main transition energies are observed: (i) PTCDA HE essentially mimics the behavior of isolated monomers on surfaces (particularly at submonolayer coverage), while (ii) PTCDA LE , red-shifted by ≈ 70 meV (≈ 560 cm −1), is attributed to two-dimensional densely packed aggregates. This red-shift is in remarkable accordance with previous investigations for PTCDA on NaCl(100) and, therefore, likely arises from the same physical effects, namely the formation of two-dimensional excitonic bands and the polarizability of neighboring molecules within the monolayer. In distinction from earlier studies, we conclude that the polarizabilities of the employed substrates do not constitute the dominant contribution to the molecular S 0 → S 1 transition energies observed here.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

See 2 more Smart Citations

Optical transition energies of isolated molecular monomers and weakly interacting two-dimensional aggregates

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…[122,123,131,132] It has been found that PTCDA molecules self-assemble on graphene in a similar fashion as on HOPG surface, i.e., the molecules adsorb flat on the surface with their aromatic core parallel to the basal plane of graphene. The supramolecular structure is stabilized both by molecule-graphene π-π interactions and by intermolecular C-H … O-C hydrogen bonds.…”

Section: Non-covalent Functionalization Of Graphene: Towards Structurmentioning

confidence: 99%

Supramolecular Approaches to Graphene: From Self‐Assembly to Molecule‐Assisted Liquid‐Phase Exfoliation

2016

View full text Add to dashboard Cite

Graphene, a one-atom thick two-dimensional (2D) material, is at the core of an ever-growing research effort due to its combination of unique mechanical, thermal, optical and electrical properties. Two strategies are being pursued for the graphene production: the bottom-up and the top-down. The former relies on the use of covalent chemistry approaches on properly designed molecular building blocks undergoing chemical reaction to form 2D covalent networks. The latter occurs via exfoliation of bulk graphite into individual graphene sheets. Amongst the various types of exfoliations exploited so far, ultrasound-induced liquid-phase exfoliation (UILPE) is an attractive strategy, being extremely versatile, up-scalable and applicable to a variety of environments. In this review, we highlight the recent developments that have led to successful non-covalent functionalization of graphene and how the latter can be exploited to promote the process of molecule-assisted UILPE of graphite. The functionalization of graphene with non-covalently interacting molecules, both in dispersions as well as in dry films, represents a promising and modular approach to tune various physical and chemical properties of graphene, eventually conferring to such a 2D system a multifunctional nature.

show abstract

π Band Folding and Interlayer Band Filling of Graphene upon Interface Potassium Intercalation

Huempfner

Otto

Fritz

et al. 2022

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

The structural and electronic properties of epitaxial monolayer graphene on SiC(0001) are examined upon potassium intercalation. Notably, the first real‐space observation via scanning tunneling microscopy of the (2 × 2) superstructure in graphene‐based thin films formed by the potassium atoms below the uppermost graphene layer is presented. Therein, additional signatures stemming from quasiparticle interference effects are found allowing investigations of the electronic bands of K‐intercalated epitaxial monolayer graphene on a local scale. Those data are compared to area‐averaged results obtained from photoelectron spectroscopy. In particular, backfolding of the graphene π bands are found as a consequence of the (2 × 2) superstructure of the K atoms with respect to the graphene lattice. This is accompanied by a strong n‐type doping effect that causes a rigid shift of the Dirac bands to higher binding energies and filling of two parabolic interlayer bands at the Γ point of the surface Brillouin zone of the graphene lattice as well. This electronic configuration is promoted by additional penetration of potassium atoms into the interspace between the SiC substrate and the buffer layer that is located between the substrate and the quasi‐freestanding graphene sheet. Consequently, the epitaxial monolayer graphene sample transforms to n‐doped epitaxial bilayer graphene upon K intercalation.

show abstract

Highly ordered growth of PTCDA on epitaxial bilayer graphene

Cited by 26 publications

References 39 publications

Optical transition energies of isolated molecular monomers and weakly interacting two-dimensional aggregates

Optical transition energies of isolated molecular monomers and weakly interacting two-dimensional aggregates

Supramolecular Approaches to Graphene: From Self‐Assembly to Molecule‐Assisted Liquid‐Phase Exfoliation

π Band Folding and Interlayer Band Filling of Graphene upon Interface Potassium Intercalation

Contact Info

Product

Resources

About