Electronic Decoupling of Aromatic Molecules from a Metal by an Atomically Thin Organic Spacer

Forker, Roman; Kasemann, Daniel; Dienel, Thomas; Wagner, Christian; Franke, Robert; Müllen, Kläus; Fritz, Torsten

doi:10.1002/adma.200801112

Cited by 38 publications

(39 citation statements)

References 28 publications

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“…2. This means in turn that h-BN serves as a decoupling insulator, a behavior which has been reported before also for a hexa-peri-hexabenzocoronene monolayer on Au(111) and its effect on subsequently grown quaterrylene molecules [50].…”

Section: B Optical In Situ Drs Measurementssupporting

confidence: 70%

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

et al. 2016

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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.

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Section: B Optical In Situ Drs Measurementssupporting

confidence: 70%

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

et al. 2016

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“…It was found that 1 ML of HBC completely decouples the on-top grown QT electronically from the metal substrate. [199] These monolayer-based A/B systems are expected to be studied further in the future as model systems for both structural relationship as well as the electronic structure at the organic-organic interface.…”

Section: Stacked Monolayers (A/b-type)mentioning

confidence: 99%

Organic–Organic Heterostructures: Concepts and Applications

2012

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We review basic concepts as well as recent examples and applications of organic-organic heterostructures. We organize the different types of heterostructures according to material A deposited on material B (A/B), A co-deposited with B (A:B), heterostructures in the monolayer regime including nanostructuring concepts and systems involving self-assembled monolayers, as well as various other architectures, including superlattices. While most examples are related to small-molecule organic semiconductors, many of the ideas can be applied to other systems. The central theme is growth and structure as well as optical and electronic properties. Finally, we comment on implications for device applications.

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“…This situation leads to rather broad and unstructured optical absorption bands usually combined with a strong spectral shift. 34,35,45 Consequently, the resulting spectra bear no resemblance to the monomer spectra (cf. Fig.…”

Section: Acs Paragon Plus Environmentmentioning

confidence: 99%

Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

et al. 2015

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We investigate the prototypical hybrid interface formed between PTCDA and conductive ndoped ZnO films by means of complementary optical and electronic spectroscopic techniques.We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level, but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction.

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Electronic Decoupling of Aromatic Molecules from a Metal by an Atomically Thin Organic Spacer

Cited by 38 publications

References 28 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

Organic–Organic Heterostructures: Concepts and Applications

Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface

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