Electronic and optical gap renormalization in carbon nanotubes near a metallic surface

Spataru, Catalin D.

doi:10.1103/physrevb.88.125412

Cited by 32 publications

(54 citation statements)

References 55 publications

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“…Furthermore, recent quasiparticle band structure calculations suggested a B2.9 eV bandgap, and hence a much larger exciton binding energy of B1.0 eV for free-standing SL MoS 2 (refs 39-42). The difference between our measurements and theoretical calculations is attributed to substrate screening effects, which has also been observed for semiconducting carbon nanotubes on metallic substrates 43,44 . The similarity of exciton binding energies obtained for MoS 2 and MoSe 2 both on graphitic substrates might indicate that the metallic substrate plays a dominant role in determining the exciton property for MoX 2 monolayers.…”

Section: Resultscontrasting

confidence: 42%

Bandgap tunability at single-layer molybdenum disulphide grain boundaries

et al. 2015

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Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85 ± 0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

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Section: Resultscontrasting

confidence: 42%

Bandgap tunability at single-layer molybdenum disulphide grain boundaries

et al. 2015

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“…Image charge (IC) corrections 29,30 are included a posteriori to account for the polarization of the metallic substrate. Despite its simplicity, the IC approximation has proven successful to evaluate both the fundamental electronic 29 and optical 30,31 gaps in weakly coupled systems. The first-principles optical response (e 2 ) computed for the isolated 7-AGNR is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Exciton-dominated optical response of ultra-narrow graphene nanoribbons

et al. 2014

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Narrow graphene nanoribbons exhibit substantial electronic bandgaps and optical properties fundamentally different from those of graphene. Unlike graphene-which shows a wavelength-independent absorbance for visible light-the electronic bandgap, and therefore the optical response, of graphene nanoribbons changes with ribbon width. Here we report on the optical properties of armchair graphene nanoribbons of width N ¼ 7 grown on metal surfaces. Reflectance difference spectroscopy in combination with ab initio calculations show that ultranarrow graphene nanoribbons have fully anisotropic optical properties dominated by excitonic effects that sensitively depend on the exact atomic structure. For N ¼ 7 armchair graphene nanoribbons, the optical response is dominated by absorption features at 2.1, 2.3 and 4.2 eV, in excellent agreement with ab initio calculations, which also reveal an absorbance of more than twice the one of graphene for linearly polarized light in the visible range of wavelengths.

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“…24 To make calculations of interfacial light-matter interactions feasible, we have developed our own implementation 26,37 of the G 0 [W 0 + ∆W]-BSE method. [41][42][43][44][45] In this approach, the substrate is included only via its screening ∆W at both the quasiparticle G 0 W 0 and BSE level. This dramatically reduces the unit cell, number of electrons, and number of unoccupied bands required in the G 0 W 0 and BSE calculations, since the substrate is only included through its screening ∆W.…”

Section: Introductionmentioning

confidence: 99%

Tailoring a Molecule’s Optical Absorbance Using Surface Plasmonics

Mowbray

Despoja

2019

J. Phys. Chem. C

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Understanding the interaction of light with molecules physisorbed on substrates is a fundamental problem in photonics, with applications in biosensing, photovoltaics, photocatalysis, plasmonics, and nanotechnology. However, the design of novel functional materials in silico is severely hampered by the lack of robust and computationally efficient methods for describing both molecular absorbance and screening on substrates. Here we employ our hybrid G 0 [W 0 + ∆W]-BSE implementation, which incorporates the substrate via its screening ∆W at both the quasiparticle G 0 W 0 level and when solving the Bethe-Salpeter equation (BSE). We show this method can be used to both efficiently and accurately describe the absorption spectra of physisorbed molecules on metal substrates and thereby tailor the molecule's absorbance by altering the surface plasmon's energy. Specifically, we investigate how the optical absorption spectra of three prototypical π-conjugated molecules: benzene (C 6 H 6 ), terrylene (C 30 H 16 ) and fullerene (C 60 ), depends on the Wigner-Seitz radius r s of the metallic substrate. To gain further understanding of the light-molecule/substrate interaction, we also study the bright exciton's electron and hole densities and their interactions with infrared active vibrational modes. Our results show that (1) benzene's bright E 1 1u exciton at 7.0 eV, whose energy is insensitive to changes in r s , could be relevant for photocatalytic dehydrogenation and polymerization reactions, (2) terrylene's bright B 3u exciton at 2.3 eV hybridizes with the surface plasmon, allowing the tailoring of the excitonic energy and optical activation of a surface plasmon-like exciton, and (3) fullerene's π − π * bright and dark excitons at 6.4 and 6.8 eV hybridize with the surface plasmon, resulting in the tailoring of their excitonic energy and the activation of both a surface plasmon-like exciton and a dark quadrupolar mode via symmetry breaking by the substrate. This work demonstrates how a proper description of interfacial light-molecular/substrate interactions enables the prediction, design, and optimization of technologically relevant phenomena in silico. arXiv:1910.05434v1 [cond-mat.mes-hall]

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Electronic and optical gap renormalization in carbon nanotubes near a metallic surface

Cited by 32 publications

References 55 publications

Bandgap tunability at single-layer molybdenum disulphide grain boundaries

Bandgap tunability at single-layer molybdenum disulphide grain boundaries

Exciton-dominated optical response of ultra-narrow graphene nanoribbons

Tailoring a Molecule’s Optical Absorbance Using Surface Plasmonics

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