Hexagonal graphene quantum dots

Ghosh, Sumit; Schwingenschlögl, Udo

doi:10.1002/pssr.201600226

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…Thus, the arm‐chair and zig‐zag orientation at the edges of CQDs play an instrumental role to determine their respective blueshift and redshift. [ 32,138,203 ] The pH dependence of PL supports the mechanism stated above. [ 202 ] The CQDs emit strong PL under alkaline conditions whereas PL is quenched in an acidic environment.…”

Section: Photophysical Properties Of Cqdssupporting

confidence: 64%

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Doping and Surface Modification of Carbon Quantum Dots for Enhanced Functionalities and Related Applications

John

Nair

2021

Part & Part Syst Charact

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Carbon quantum dots (CQDs) are a unique class of 0D nanomaterials, featured by a graphitic core and shell layers saturated with hydrogen atoms and functional groups. CQDs are prepared through top‐down and bottom‐up strategies from natural and synthetic precursors. CQDs can be modified through chemical (e.g., surface functionalization/passivation, doping, etc.) and physical (e.g., core–shell architecture, composite material blending, etc.) strategies to control their properties. This review highlights the effect of such modifications on the photophysical properties of CQDs, such as photoluminescence (PL), absorbance, and relaxivity. The dependence of PL upon the size, orientation at the edges, surface and edge functionalization, doping, excitation wavelength, concentration, pH, aggregate formation, etc., are summarized along with the supporting theoretical evidence available in the literature. Also, this review outlines the recent advancements, and future prospective of optical (e.g., sensing, bioimaging, and fluorescent ink) and catalytic applications (e.g., photocatalysis and electrocatalysis) of CQDs enhanced through physical and chemical modifications of their structure and composition.

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Section: Photophysical Properties Of Cqdssupporting

confidence: 64%

“…[ 31 ] The aforementioned experimental advancements in CQD research were sporadically powered by theoretical interpretations from density functional theory (DFT) and time‐dependent DFT (TD‐DFT) studies depicting doping, functionalization/passivation, etc. [ 32–34 ]…”

Section: Introductionmentioning

confidence: 99%

Doping and Surface Modification of Carbon Quantum Dots for Enhanced Functionalities and Related Applications

John

Nair

2021

Part & Part Syst Charact

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“…There is currently significant interest in the electronic and optical properties of graphene quantum dots (GQDs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Since graphene is a semi-metal [18][19][20][21][22][23], lateral size quantization potentially allows for the creation of a material with continuously tunable bandgap that ranges from THz to UV.…”

Section: Introductionmentioning

confidence: 99%

Oscillations of the bandgap with size in armchair and zigzag graphene quantum dots

Saleem

Baldo

Delgado

et al. 2019

J. Phys.: Condens. Matter

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We determine here the evolution of the bandgap energy with size in graphene quantum dots (GQDs). We find oscillatory behaviour of the bandgap and explain its origin in terms of armchair and zigzag edges. The electronic energy spectra of GQDs are computed using both the tight binding model and ab initio density functional methods. The results of the tight binding model are analyzed by dividing zigzag graphene quantum dots into concentric rings. For each ring, the energy spectra, the wave functions and the bandgap are obtained analytically. The effect of inter-ring tunneling on the energy gap is determined. The growth of zigzag terminated GQD into armchair GQD is shown to be associated with the addition of a one-dimensional Lieb lattice of carbon atoms with a shell of energy levels in the middle of the energy gap of the inner zigzag terminated GQD. This introduces a different structure of the energy levels at the bottom of the conduction and top of the valence band in zigzag and armchair GQD which manifests itself in the oscillation of the energy gap with increasing size. The evolution of the bandgap with the number of carbon atoms is compared with the notion of confined Dirac Fermions and tested against ab initio calculations of Kohn-Sham and TD-DFT energy gaps.

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“…Although the transport properties of carbon nanoribbons and CNTs have been extensively studied, GSs have not been yet thoroughly investigated. Moreover, the physical properties of the hexagonal GQDs and triangle GQDs have distinctive difference [24][25][26][27][28][29]. Therefore, studies on TGSs and their properties are highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Strain-induced tunable negative differential resistance in triangle graphene spirals

et al. 2018

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Using non-equilibrium Green's function formalism combined with density functional theory calculations, we investigate the significant changes in electronic and transport properties of triangle graphene spirals (TGSs) in response to external strain. Tunable negative differential resistance (NDR) behavior is predicted. The NDR bias region, NDR width, and peak-to-valley ratio can be well tuned by external strain. Further analysis shows that these peculiar properties can be attributed to the dispersion widths of the p orbitals. Moreover, the conductance of TGSs is very sensitive to the applied stress, which is promising for applications in nanosensor devices. Our findings reveal a novel approach to produce tunable electronic devices based on graphene spirals.

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Hexagonal graphene quantum dots

Cited by 5 publications

References 38 publications

Doping and Surface Modification of Carbon Quantum Dots for Enhanced Functionalities and Related Applications

Doping and Surface Modification of Carbon Quantum Dots for Enhanced Functionalities and Related Applications

Oscillations of the bandgap with size in armchair and zigzag graphene quantum dots

Strain-induced tunable negative differential resistance in triangle graphene spirals

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