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Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation…

We investigate optical absorption spectra obtained through time-dependent density functional theory (TD-DFT) based on nonempirical hybrid functionals that are designed to correctly reproduce the dielectric function. The comparison with…

Materials Science · Physics 2020-08-17 Alexey Tal , Peitao Liu , Georg Kresse , Alfredo Pasquarello

A 200 mm processing platform for the large-scale production of graphene field-effect transistor-quantum dot (GFET-QD) hybrid photodetectors is demonstrated. Comprehensive statistical analysis of electric data shows a high yield (96%) and…

Charge transfer complexes are materials with a wide range of interesting optical and electronic properties. They have seen a great deal of research over the past decade, both in device development as well as research to elucidate the…

Materials Science · Physics 2024-06-04 Satwik Ramanjanappa , Edward R Van Keuren

Graphene quantum dots (GQDs) represent single layers up to dozens of graphene layers smaller than 30 nm. GQDs are newish molecules that have aroused great interest in research because of their exceptional and manageable optical, electrical,…

Materials Science · Physics 2021-01-20 Setianto Setianto , Liu Kin Men , Camellia Panatarani , I Made Joni

We use density functional theory (DFT) with a recently developed van der Waals density functional (vdW-DF) to study the adsorption of graphene on Al, Cu, Ag, Au, Pt, Pd, Co and Ni(111) surfaces. In constrast to the local density…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 M. Vanin , J. J. Mortensen , A. K. Kelkkanen , J. M. Garcia-Lastra , K. S. Thygesen , K. W. Jacobsen

Density functional theory (DFT) modeling of the physisorption of four different types of molecules (toluene, bromine dimmer, water and nitrogen dioxide) over and above graphene ripples has been performed. For all types of molecules changes…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 D. W. Boukhvalov

We study the optical properties of hydrogen passivated silicon, germanium and mixed Ge/Si core/shell quantum dots (QDs) using high accuracy Density Functional Theory (DFT) and time-dependent DFT (TDFT). We employ the hybrid DFT functional…

Mesoscale and Nanoscale Physics · Physics 2016-04-19 Shanawer Niaz , Aristides D. Zdetsis , Manzoor Ahmad Badar , Safdar Hussain , Imran Sadiq , Muhammad Aslam Khan

Recent progress in the synthesis of highly stable, eco-friendly, cost-effective transition metal-dichalcogenides (TMDC) quantum dots (QDs) with their broadband absorption spectrum and wavelength selectivity features have led to their…

A one-dimensional dielectric grating, based on a simple geometry, is proposed and investigated to enhance light absorption in a monolayer graphene exploiting guided mode resonances. Numerical findings reveal that the optimized configuration…

Spin-polarized first-principles calculations have been performed to tune the electronic and optical properties of graphene (G) and boron-nitride (BN) quantum dots (QDs) through molecular charge-transfer using Tetracyanoquinodimethane (TCNQ)…

Materials Science · Physics 2017-09-13 Arkamita Bandyopadhyay , Sharma SRKC Yamijala , Swapan K Pati

We numerically and experimentally investigate graphene-based optical absorbers that exploit guided mode resonances (GMRs) achieving perfect absorption over a bandwidth of few nanometers (over the visible and near-infrared ranges) with a…

Doping a self-assembled InGaAs/GaAs quantum dot (QD) with a single Mn atom, a magnetic acceptor impurity, provides a quantum system with discrete energy levels and original spin-dependent optical selection rules, which thus has large…

Mesoscale and Nanoscale Physics · Physics 2024-10-28 Jovana Filipovic , Ankit Kundu , Neelesh Kumar Vij , Simon Fécherolle , Aristide Lemaître , Shilpi Gupta , Olivier Krebs

We present a systematic theoretical study of the five smallest oligoacenes (naphthalene, anthracene, tetracene, pentacene, and hexacene) in their anionic,neutral, cationic, and dicationic charge states. We used density functional theory…

Chemical Physics · Physics 2009-11-13 G. Malloci , G. Mulas , G. Cappellini , C. Joblin

The layer stacking morphology in nanocarbons is paramount for achieving new properties and outperforming applications. Here, we demonstrate that graphene quantum dots (GQDs) retain crystallinity and a stacking structure from CVD graphene…

Graphene is an attractive material for broadband photodetection but suffers from weak light absorption. Coating graphene with quantum dots can significantly enhance light absorption and create extraordinarily high photo gain. This high gain…

Mesoscale and Nanoscale Physics · Physics 2020-12-04 Kaixiang Chen , Chufan Zhang , Xiaoxian Zang , Fuyuan Ma , Yuanzhen Chen , Yaping Dan

We formulate a time-dependent density functional theory (TDDFT) in terms of the density matrix to study ultrafast phenomena in semiconductor structures. A system of equations for the density matrix components, which is equivalent to the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 V. Turkowski , C. A. Ullrich

In this work, we report for the first time the crucial role of topological anomalies like Stone-Wales (SW) type bond rotations in tuning the optical properties of graphene quantum dots (GQDs). By means of first-principles calculations, we…

Mesoscale and Nanoscale Physics · Physics 2021-06-17 Tista Basak , Tushima Basak , Alok Shukla

When a chromophore interacts with titrable molecular sites, the modeling of its photophysical properties requires to take into account all their possible protonation states. We have developed a multi-scale protocol, based on constant-pH…

Chemical Physics · Physics 2018-09-10 Elisa Pieri , Vincent Ledentu , Nicolas Ferré

Using density functional theory calculations, we have examined the structural stability, electronic, magnetic and optical properties of rectangular shaped quantum dots (QDs) of graphene (G), Boron Nitride (BN) and their hybrids. Different…

Materials Science · Physics 2013-11-14 Sharma SRKC Yamijala , Arkamita Bandyopadhyay , Swapan K Pati