Excitonic States in Narrow Armchair Graphene Nanoribbons on Gold Surfaces

Bronner, Christopher; Gerbert, David; Broska, A.; Tegeder, Petra

doi:10.1021/acs.jpcc.6b10834

Cited by 14 publications

(12 citation statements)

References 42 publications

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“…6, we summarize the level alignments with respect to the vacuum level (E vac ). As discussed previously [28,29,50], one has to consider that electronic states determined by STS are transport states because electron tunneling into unoccupied molecular states results in the formation of negative ion resonances. On the other hand, tunneling out of occupied molecular states leads to the creation of positive ion resonances.…”

Section: Resultsmentioning

confidence: 99%

Electronic structure of an iron porphyrin derivative on Au(1 1 1)

Stein

Rolf

Lotze

et al. 2018

J. Phys.: Condens. Matter

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Surface-bound porphyrins are promising candidates for molecular switches, electronics and spintronics. Here, we studied the structural and the electronic properties of Fe-tetra-pyridil-porphyrin adsorbed on Au(111) in the monolayer regime. We combined scanning tunneling microscopy/spectroscopy, ultraviolet photoemission, and two-photon photoemission to determine the energy levels of the frontier molecular orbitals. We also resolved an excitonic state with a binding energy of 420 meV, which allowed us to compare the electronic transport gap with the optical gap.

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Section: Resultsmentioning

confidence: 99%

Electronic structure of an iron porphyrin derivative on Au(1 1 1)

Stein

Rolf

Lotze

et al. 2018

J. Phys.: Condens. Matter

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“…The electronic structure of GNRs and in particular their band gap (E g ) size and the values of bands' effective masses (m VB and m CB ), have been addressed locally with scanning tunneling spectroscopy (STS) [34,40,42,43,45,46,50,51], and with average experimental techniques as angle-resolved-, inverse-and two-photonphotoemission [34,35,[52][53][54], high-resolution electron energy loss [52,55] and optical spectroscopy [56].…”

Section: Graphene Nanoribbon´s Electronic Properties Determinationmentioning

confidence: 99%

Bottom-Up Fabrication of Atomically Precise Graphene Nanoribbons

Corso

Carbonell-Sanromà

Oteyza

2018

On-Surface Synthesis II

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Graphene nanoribbons (GNRs) make up an extremely interesting class of materials. On the one hand GNRs share many of the superlative properties of graphene, while on the other hand they display an exceptional degree of tunability of their optoelectronic properties. The presence or absence of correlated lowdimensional magnetism, or of a widely tunable band gap, is determined by the boundary conditions imposed by the width, crystallographic symmetry and edge structure of the nanoribbons. In combination with additional controllable parameters like the presence of heteroatoms, tailored strain, or the formation of heterostructures, the possibilities to shape the electronic properties of GNRs according to our needs are fantastic. However, to really benefit from that tunability and harness the opportunities offered by GNRs, atomic precision is strictly required in their synthesis. This can be achieved through an on-surface synthesis approach, in which one lets appropriately designed precursor molecules to react in a selective way that ends up forming GNRs. In this chapter we review the structure-property relations inherent to GNRs, the synthesis approach and the ways in which the varied properties of the resulting ribbons have been probed, finalizing with selected examples of demonstrated GNR applications.

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“…The nature and dynamics of the excitonic states are of great interest as they are directly related to application-related processes such as light absorption and emission, photoconductivity, and electroluminescence and thus have motivated several recent studies. For instance, two previous experimental studies on quantifying the exciton binding effect in a seven C atom wide armchair nanoribbon (7-AGNRs) on gold substrates have been conducted employing reflectance difference spectroscopy and angle-resolved two-photon photoemission spectroscopy . However, due to a polarization effect from the substrate, a modest E B value of ∼160 meV was reported by Bronner et al, much smaller than the theoretical value of 1.8 eV for the same GNRs in the gas phase .…”

Section: Introductionmentioning

confidence: 96%

Experimental Observation of Strong Exciton Effects in Graphene Nanoribbons

et al. 2020

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Graphene nanoribbons (GNRs) with atomically precise width and edge structures are a promising class of nanomaterials for optoelectronics, thanks to their semiconducting nature and high mobility of charge carriers. Understanding the fundamental static optical properties and ultrafast dynamics of charge carrier generation in GNRs is essential for optoelectronic applications. Combining THz spectroscopy and theoretical calculations, we report a strong exciton effect with binding energy up to ∼700 meV in liquid-phase-dispersed GNRs with a width of 1.7 nm and an optical band gap of ∼1.6 eV, illustrating the intrinsically strong Coulomb interactions between photogenerated electrons and holes. By tracking the exciton dynamics, we reveal an ultrafast formation of excitons in GNRs with a long lifetime over 100 ps. Our results not only reveal fundamental aspects of excitons in GNRs (strong binding energy and ultrafast exciton formation etc.) but also highlight promising properties of GNRs for optoelectronic devices.

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Excitonic States in Narrow Armchair Graphene Nanoribbons on Gold Surfaces

Cited by 14 publications

References 42 publications

Electronic structure of an iron porphyrin derivative on Au(1 1 1)

Electronic structure of an iron porphyrin derivative on Au(1 1 1)

Bottom-Up Fabrication of Atomically Precise Graphene Nanoribbons

Experimental Observation of Strong Exciton Effects in Graphene Nanoribbons

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