Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons

We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit unique excitation peaks, and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discovered the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.

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Role Played by Edge-Defects in the Optical Properties of Armchair Graphene Nanoribbons

10.20944/preprints202110.0427.v1 ◽

2021 ◽

Author(s):

Thi-Nga Do ◽

Godfrey Gumbs ◽

Danhong Huang ◽

D. Hoi Bui ◽

Po-Hsin Shih

Keyword(s):

Optical Properties ◽

Graphene Nanoribbons ◽

Tight Binding ◽

Edge States ◽

Binding Model ◽

Edge Defect ◽

Flat Bands ◽

Edge Defects ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

We explore the implementation of specific optical properties of armchair graphene nanoribbons (AGNRs) through edge-defect manipulation. This technique employs the tight-binding model in conjunction with the calculated absorption spectral function. Modification of the edge states gives rise to the diverse electronic structures with striking changes in the band gap and special flat bands at low energy. The optical-absorption spectra exhibit exotic excitation peaks and they strongly depend on the type and period of the edge extension. Remarkably, there exist the unusual transition channels associated with the flat bands for selected edge-modified systems. We discover the special rule governing how the edge-defect influences the electronic and optical properties in AGNRs. Our theoretical prediction demonstrates an efficient way to manipulate the optical properties of AGNRs. This might be of importance in the search for suitable materials designed to have possible technology applications in nano-optical, plasmonic and optoelectronic devices.

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Multi-orbital tight binding model for the electronic and optical properties of armchair graphene nanoribbons in the presence of a periodic potential

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/abdf01 ◽

2021 ◽

Author(s):

Nguyen N. Hieu ◽

Po-Hsin Shih ◽

Thi-Nga Do ◽

Chuong Nguyen

Keyword(s):

Optical Properties ◽

Periodic Potential ◽

Graphene Nanoribbons ◽

Tight Binding ◽

Tight Binding Model ◽

Binding Model ◽

Electronic And Optical Properties ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

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Intrinsic Spin-Orbit Coupling in Zigzag and Armchair Graphene Nanoribbons

Journal of Nanomaterials ◽

10.1155/2011/364897 ◽

2011 ◽

Vol 2011 ◽

pp. 1-7

Author(s):

Ying Li ◽

Erhu Zhang ◽

Baihua Gong ◽

Shengli Zhang

Keyword(s):

Graphene Nanoribbons ◽

Tight Binding ◽

Geometrical Parameters ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Binding Model ◽

Tight Binding Approximation ◽

Energy Gaps ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

Starting from a tight-binding model, we derive the energy gaps induced by intrinsic spin-orbit (ISO) coupling in the low-energy band structures of graphene nanoribbons. The armchair graphene nanoribbons may be either semiconducting or metallic, depending on their widths in the absence of ISO interactions. For the metallic ones, the gaps induced by ISO coupling decrease with increasing ribbon widths. For the ISO interactions, we find that zigzag graphene nanoribbons with odd chains still have no band gaps while those with even chains have gaps with a monotonic decreasing dependence on the widths. First-principles calculations have also been carried out, verifying the results of the tight-binding approximation. Our paper reveals that the ISO interaction of graphene nanoribbons is governed by their geometrical parameters.

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Effects of band hybridization on electronic properties in tuning armchair graphene nanoribbons

Canadian Journal of Physics ◽

10.1139/cjp-2015-0066 ◽

2016 ◽

Vol 94 (2) ◽

pp. 218-225 ◽

Cited By ~ 3

Author(s):

M. Khatun ◽

Z. Kan ◽

A. Cancio ◽

C. Nelson

Keyword(s):

Fermi Level ◽

Density Of States ◽

Graphene Nanoribbons ◽

Local Density ◽

Tight Binding ◽

Edge States ◽

Local Density Of States ◽

Periodic Patterns ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

We explore a model of armchair graphene nanoribbons tuned by functionalizing the edge states. Edge modifications are modeled by changing the electronic energy of the edge states in specific periodic patterns. The model can be considered to mimic a controlled doping process with different elements. The band structure, density of states, conductance, and local density of states are calculated, using the tight binding approach, Green’s function methodology, and the Landauer formula. The results show interesting behaviors, which are considerably different from the properties of the perfect nanoribbons. The hybridization of conducting bands with non-conducting bands, which appear perfectly flat in the perfect ribbon, opens up and modifies gaps in conductance near the Fermi level. One particular pattern of edge functionalization causes a strong, symmetric, and systematic band gap change about the Fermi level, modifying the electronic characteristics in the energy dispersion, density of states, local density of states, and conductance.

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Electronic and optical properties of surface-functionalized armchair graphene nanoribbons

RSC Advances ◽

10.1039/c5ra22701a ◽

2016 ◽

Vol 6 (28) ◽

pp. 23974-23980 ◽

Cited By ~ 8

Author(s):

Min Wang ◽

Si Xing Song ◽

Hai Xing Zhao ◽

Yu Chen Wang

Keyword(s):

Optical Properties ◽

Spatial Distribution ◽

Functional Groups ◽

Graphene Nanoribbons ◽

Electronic And Optical Properties ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

The functional groups on armchair graphene nanoribbons affect the spatial distribution of the wavefunction and influence the electronic and optical properties as well.

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Exciton effects in strained armchair graphene nanoribbons

International Journal of Modern Physics B ◽

10.1142/s0217979216500211 ◽

2016 ◽

Vol 30 (06) ◽

pp. 1650021 ◽

Cited By ~ 2

Author(s):

Yonglei Jia ◽

Junlin Liu

Keyword(s):

Binding Energy ◽

Excitation Energy ◽

Graphene Nanoribbons ◽

Tight Binding ◽

Uniaxial Strain ◽

Exciton Binding Energy ◽

Coulomb Interactions ◽

Optomechanical Systems ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

The exciton effects in 1-nm-wide armchair graphene nanoribbons (AGNRs) under the uniaxial strain were studied within the nonorthogonal tight-binding (TB) model, supplemented by the long-range Coulomb interactions. The obtained results show that both the excitation energy and exciton binding energy are modulated by the uniaxial strain. The variation of these energies depends on the ribbon family. In addition, the results show that the variation of the exciton binding energy is much weaker than the variation of excitation energy. Our results provide new guidance for the design of optomechanical systems based on graphene nanoribbons.

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Topological edge states on time-periodically strained armchair graphene nanoribbons

Physical Review B ◽

10.1103/physrevb.96.155435 ◽

2017 ◽

Vol 96 (15) ◽

Cited By ~ 14

Author(s):

Pedro Roman-Taboada ◽

Gerardo G. Naumis

Keyword(s):

Graphene Nanoribbons ◽

Edge States ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

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Electronic and Optical Properties of the Narrowest Armchair Graphene Nanoribbons Studied by Density Functional Methods

Australian Journal of Chemistry ◽

10.1071/ch16187 ◽

2016 ◽

Vol 69 (9) ◽

pp. 960 ◽

Cited By ~ 6

Author(s):

Chia-Nan Yeh ◽

Pei-Yin Lee ◽

Jeng-Da Chai

Keyword(s):

Density Functional Theory ◽

Optical Properties ◽

Ground State ◽

Density Functional ◽

Graphene Nanoribbons ◽

Finite Size ◽

Functional Theory ◽

Electronic And Optical Properties ◽

Armchair Graphene Nanoribbons ◽

Armchair Graphene

In the present study, a series of planar poly(p-phenylene) (PPP) oligomers with n phenyl rings (n = 1–20), designated as n-PP, are taken as finite-size models of the narrowest armchair graphene nanoribbons with hydrogen passivation. The singlet-triplet energy gap, vertical ionization potential, vertical electron affinity, fundamental gap, optical gap, and exciton binding energy of n-PP are calculated using Kohn-Sham density functional theory and time-dependent density functional theory with various exchange-correlation density functionals. The ground state of n-PP is shown to be singlet for all the chain lengths studied. In contrast to the lowest singlet state (i.e., the ground state) of n-PP, the lowest triplet state of n-PP and the ground states of the cation and anion of n-PP are found to exhibit some multi-reference character. Overall, the electronic and optical properties of n-PP obtained from the ωB97 and ωB97X functionals are in excellent agreement with the available experimental data.

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