Molecule–substrate interaction in functionalized graphene

Berghäuser, Gunnar; Malić, Ermin

doi:10.1016/j.carbon.2013.12.063

Cited by 12 publications

(23 citation statements)

References 43 publications

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“…Evaluating Eq. (2), one can see that the microscopic polarization p With this assumption, we find an analytic solution for the hybrid Bloch equation in the Fourier-space and in the limit k = k (relevant for the linear optical response): [18] …”

Section: Functionalized Graphenementioning

confidence: 99%

“…[18,[46][47][48][49][50] Beside optically accessible bright excitons located at the K valley, TMDs also show a variety of optically forbidden (dark) excitons, which either exhibit different spins or non-vanishing angular or center-of-mass momenta. [51][52][53][54] In this work, we focus on the latter class of dark excitons and in particular on the dark K exciton, where the hole is located at the K and the electron at the valley, cf.…”

Section: Functionalized Transition Metal Dichalcogenidesmentioning

confidence: 99%

“…Applying nearest-neighbor tight-binding wave functions and exploiting the periodic molecular lattice on the surface of the carbon nanomaterial, we obtain for the carrier-molecule coupling element in the case of one-dimensional carbon nanoribbons (lying in x direction) [18,43] …”

Section: Functionalized Graphenementioning

confidence: 99%

“…To obtain the absorption coefficient α(ω), we solve the Heisenberg equation of motion for p [12,18] resulting from the molecular dipole moment d from all attached molecules m. This external dipole field depends on the molecular dipole orientation α with respect to the surface of the functionalized nanomaterial as well as on the molecular coverage scaling with the molecular distance R z , cf. Figure 2(b).…”

Section: Theoretical Approachmentioning

confidence: 99%

“…[12,18,28] They consist of a coupled system of differential equations for the carrier occupation probabilities ρ λ k = a + λk a λk and the microscopic polarization p k that has already been introduced above. Since we are interested in describing a linear absorption spectrum, the driving field is considered to be small resulting in a negligible change of the carrier occupations.…”

Section: Theoretical Approachmentioning

confidence: 99%

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Optical Response From Functionalized Atomically Thin Nanomaterials

et al. 2017

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Chemical functionalization of atomically thin nanostructures presents a promising strategy to create new hybrid nanomaterials with remarkable and externally controllable properties. Here, we review our research in the field of theoretical modeling of carbon nanotubes, graphene, and transition metal dichalcogenides located in molecular dipole fields. In particular, we provide a microscopic view on the change of the optical response of these technologically promising nanomaterials due to the presence of photo-active spiropyran molecules. The feature article presents a review of recent theoretical work providing microscopic view on the optical response of chemically functionalized carbon nanotubes, graphene, and monolayered transition metal dichalcogenides. In particular, we propose a novel sensor mechanism based on the molecule-induced activation of dark excitons. This results in a pronounced additional peak presenting an unambiguous optical fingerprint for the attached molecules.The adsorption of molecules to the surface of atomically thin nanostructures opens a new field of hybrid materials with externally tunable properties. Consisting of a single layer of atoms, these materials show an optimal surface-to-volume ratio resulting in extremely high sensitivity to changes in their surrounding. In particular, their optical properties directly reflect the presence of externally attached molecules. As a result, the optical response can be exploited for engineering novel chemical sensors molecular switches, and nanoscale photodetectors. [5,9,16,[23][24][25] Promising candidates for the functionalization of nanomaterials are photoactive molecules. The most prominent representative of this class of molecules are spiropyrans, which can be reversibly switched between the open planar merocyanine (MC) and the closed orthogonal spiropyran (SP) conformation. The corresponding ring-opening/ring-closing process is driven by visible and ultraviolet light, respectively, [26] cf. control the coupling between the molecule and the excitons in the nanomaterial. The key for designing and engineering devices based on functionalized nanomaterials is a microscopic understanding of the interaction between the adsorbed molecule and the nanomaterial. In this feature article, we present a review of our work on microscopic modeling of the optical response from carbon nanotubes, graphene, and monolayer transition metal dichalcogenides located in molecular dipole fields. Theoretical ApproachWe focus on modeling of the optical response of 1D or 2D atomically thin nanomaterials that are non-covalently functionalized with photoactive spiropyran molecules exhibiting a large dipole moment. Non-covalent functionalization via Van der Waals interaction is known to have a minor influence on electronic properties of the functionalized nanomaterial, thus it is a good approximation to assume an unchanged electronic band structure and wave functions.[4] As a result, the situation we model corresponds to a pristine nanomaterial that is located in a static di...

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Section: Functionalized Graphenementioning

confidence: 99%

Section: Functionalized Transition Metal Dichalcogenidesmentioning

confidence: 99%

Section: Functionalized Graphenementioning

confidence: 99%

Section: Theoretical Approachmentioning

confidence: 99%

Section: Theoretical Approachmentioning

confidence: 99%

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Optical Response From Functionalized Atomically Thin Nanomaterials

et al. 2017

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Optical properties of functionalized graphene

Berghäuser

Malić

2013

Phys. Status Solidi B

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Hybrid nanostructures are an emerging field in current research. The goal is to tailor material systems with desired electronic or optical properties by functionalization with molecules. Based on the density matrix formalism, we present a theoretical study on the optical properties of graphene functionalized with photoactive spiropyran molecules. Our calculations reveal the impact of the functionalization conditions on the absorption spectrum of graphene‐based hybrid nanostructures. In particular, we find that the molecular coverage has a significant effect on the optical transition energy and shape, while the molecular dipole orientation plays a minor role. The external molecular dipole field induces changes in the optical properties of graphene. Inset: The photoactive spiropyran molecules can be optically switched into the merocyanine configuration that is characterized by a pronounced dipole moment [after Guo et al., J. Am. Chem. Soc. 127(43), 15045 (2005)].

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Energy‐transfer in porphyrin‐ functionalized graphene

Malić

Appel

Hofmann

et al. 2014

Physica Status Solidi (b)

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We present a theoretical study on the molecule-substrate interaction within the porphyrin-functionalized graphene. Recent experiments on porphyrin-functionalized carbon nanotubes have revealed an extremely efficient energy transfer from the adsorbed molecules to the carbon substrate. To investigate the energy transfer mechanism, we have characterized the hybrid structure within the density functional theory including the calculation of the molecular transition dipole moment, which allows us to determine the Förster coupling rate. We find a strongly pronounced Förster-induced energy transfer in the range of fs −1 confirming the experimental observations.Side view on the graphene layer non-covalently functionalized with a porphyrin molecule.

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Molecule–substrate interaction in functionalized graphene

Cited by 12 publications

References 43 publications

Optical Response From Functionalized Atomically Thin Nanomaterials

Optical Response From Functionalized Atomically Thin Nanomaterials

Optical properties of functionalized graphene

Energy‐transfer in porphyrin‐ functionalized graphene

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