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We present time-dependent density functional theory (TDDFT) calculations of fluorescence emission energies for 284 distinct graphene quantum dots (GQDs) of varying shapes (square, hexagonal, and amorphous) and sizes ($\sim$1-2 nm). These…

Materials Science · Physics 2024-10-22 Mustafa Çoşkun Özdemir , Caner Ünlü , Şener Özönder

We have studied the electronic and optical properties of three low-symmetry graphene quantum dots (GQDs), with the point-group symmetries $C_{2v}$, and $C_{2h}$. For the calculations of linear optical absorption spectra, we employed both…

Chemical Physics · Physics 2024-12-06 Samayita Das , Alok Shukla

We propose a model based on density functional theory (DFT) and quantum electrodynamics (QED) to study the dynamical characteristics of graphene quantum dots (GQDs). We assume the GQD edges are saturated with hydrogen atoms, effectively…

Mesoscale and Nanoscale Physics · Physics 2026-04-09 J. Olivo , J. Blengino Albrieu , Mauro Cuevas

Ab-initio calculations based on density functional theory (DFT) have been performed to study the optical properties of pure graphene and have been compared to that of individual boron (B), nitrogen (N) and BN co-doped graphene sheet. The…

Mesoscale and Nanoscale Physics · Physics 2020-05-22 Pooja Rani , Girija S Dubey , V. K. Jindal

In this paper, optical and electronic properties of diamond shaped graphene quantum dots (DQDs) have been studied by employing large-scale electron-correlated calculations. The computations have been performed using the \pi-electron…

Mesoscale and Nanoscale Physics · Physics 2015-11-16 Tista Basak , Himanshu Chakraborty , Alok Shukla

Due to the advantage of tunability via size, shape, doping and relatively low level of loss and high extent of spatial confinement, graphene quantum dots (GQDs) are emerging as an effective way to control light by molecular engineering. The…

Materials Science · Physics 2015-02-13 Sharma S. R. K. C Yamijala , Madhuri Mukhopadhyay , Swapan K. Pati

Graphene monolayer is a material with zero band gap, because of which its applications in optoelectronics are limited. The question arises, can we modify the optoelectronic properties of graphene by doping it with other atoms? Synthesis of…

Materials Science · Physics 2026-03-18 Samayita Das , Alok Shukla

Quantum plasmonics of few electrons that was reported a few years ago in photodoping experiments has received little or no attention in doped nanomaterials both theoretically and experimentally. There are no studies of quantum plasmonics of…

Materials Science · Physics 2024-01-02 D Dada , M D Mochena

We have computationally investigated absorption spectra of a specifically configured set of graphene-based molecules involving (1) a sp2 bare graphene sheet; (2) framed graphene sheets containing different chemical addends terminating…

Materials Science · Physics 2017-02-24 Mikhail F. Budyka , Elena F. Sheka , Nadezhda A. Popova

Density functional theory (DFT) and thermal DFT (thDFT) calculations were used to evaluate the energy band structure, bandgap, and the total energy of various graphene quantum dots (GQDs). The DFT calculations were performed using local…

Materials Science · Physics 2021-12-20 Majid Ghandchi , Ghafar Darvish , Mohammad Kazem Moravvej-Farshi

Graphene quantum dots (GQD's) have optical properties which are very different from those of an extended graphene sheet. In this Article we explore how the size, shape and edge--structure of a GQD affect its optical conductivity. Using…

Materials Science · Physics 2018-03-14 Rico Pohle , Eleftheria G. Kavousanaki , Keshav M. Dani , Nic Shannon

Density functional theory (DFT) can be quite advantageous in advancing the field of catalysis because of the microscopic insights it provides, and thus can guide experimental searches of novel catalysts. Several recent works have…

Materials Science · Physics 2022-03-24 Vaishali Sharma , Basant Roondhe , Sumit Saxena , Alok Shukla

We present a detailed study of the optical absorption spectra of DNA bases and base pairs, carried out by means of time dependent density functional theory. The spectra for the isolated bases are compared to available theoretical and…

Materials Science · Physics 2007-05-23 D. Varsano , R. Di Felice , M. A. L. Marques , A. Rubio

A simple analysis is performed for the absorption properties of graphene; sandwiched between two media. For a proper choice of media and graphene doping/gating one can approach 50-100% absorption in the GHz-THz range for the one atom thick…

Optics · Physics 2012-01-17 S. P. Apell , G. W. Hanson , C. Hägglund

We have performed first-principles calculations to study optical absorption spectra of doped graphene with many-electron effects included. Both self-energy corrections and electron-hole interactions are reduced due to the enhanced screening…

Mesoscale and Nanoscale Physics · Physics 2011-09-09 Li Yang

Electronic properties of graphene quantum dots (GQDs) constitute a subject of intense scientific interest. Being smaller than 20 nm, GQDs contain confined excitons in all dimensions simultaneously. GQDs feature a non-zero band gap and…

Materials Science · Physics 2015-04-21 Guilherme Colherinhas , Eudes Eterno Fileti , Vitaly V. Chaban

In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNF) or graphene quantum dots (GQD) are relevant for their electronic structure, thermal stability and optical properties. Using computer…

Mesoscale and Nanoscale Physics · Physics 2016-06-15 Candela Mansilla Wettstein , Franco P. Bonafé , M. Belén Oviedo , Cristián G. Sánchez

Graphene-based photodetectors have shown responsivities up to 10$^8$A/W and photoconductive gains up to 10$^{8}$ electrons per photon. These photodetectors rely on a highly absorbing layer in close proximity of graphene, which induces a…

Density functional theory (DFT) is a powerful computational method used to obtain physical and chemical properties of materials. In the materials discovery framework, it is often necessary to virtually screen a large and high-dimensional…

Materials Science · Physics 2024-08-06 Şener Özönder , H. Kübra Küçükkartal

Using both time-dependent density functional theory (TDDFT) and the ``single-shot" $GW$ plus Bethe-Salpeter equation ($GW$-BSE) approach, we compute optical band gaps and optical absorption spectra from first principles for eight common…

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