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4 results on '"Valeriia Grigel"'

1. Interfacial Oxidation and Photoluminescence of InP-Based Core/Shell Quantum Dots

Author

Edwin A. Baquero, Dorian Dupont, Valeriia Grigel, Sara Bals, Céline Nayral, Fabien Delpech, Mickael D. Tessier, Zeger Hens, Eva Bladt, Yannick Coppel, Universiteit Gent = Ghent University (UGENT), SIM vzw, Universidad Nacional de Colombia [Bogotà] (UNAL), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Electron Microscopy for Materials Science - EMAT (Antwerp, Belgium), Universiteit Antwerpen = University of Antwerpen [Antwerpen], Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University [Belgium] (UGENT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Universiteit Antwerpen [Antwerpen], Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), and Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photoluminescence, General Chemical Engineering, Shell (structure), Oxide, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, chemistry.chemical_compound, Materials Chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, business.industry, Physics, Heterojunction, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Core (optical fiber), Chemistry, chemistry, Quantum dot, Indium phosphide, Optoelectronics, 0210 nano-technology, Luminescence, business
Abstract

International audience; Indium phosphide colloidal quantum dots (QDs) are emerging as an efficient cadmium-free alternative for optoelectronic applications. Recently, syntheses based on easy-to-implement aminophosphine precursors have been developed. We show by solid-state nuclear magnetic resonance spectroscopy that this new approach allows oxide-free indium phosphide core or core/shell quantum dots to be made. Importantly, the oxide-free core/shell interface does not help in achieving higher luminescence efficiencies. We demonstrate that in the case of InP/ZnS and InP/ZnSe QDs, a more pronounced oxidation concurs with a higher photoluminescence efficiency. This study suggests that a II–VI shell on a III–V core generates an interface prone to defects. The most efficient InP/ZnS or InP/ZnSe QDs are therefore made with an oxide buffer layer between the core and the shell: it passivates these interface defects but also results in a somewhat broader emission line width.

Published
2018
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2. InAs Colloidal Quantum Dots Synthesis via Aminopnictogen Precursor Chemistry

Author

Dorian Dupont, Zeger Hens, Valeriia Grigel, Kim De Nolf, and Mickael D. Tessier

Subjects
Infrared, Band gap, Chemistry, Nanotechnology, 02 engineering and technology, General Chemistry, engineering.material, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Condensed Matter::Materials Science, Colloid and Surface Chemistry, Coating, Quantum dot, engineering, Colloidal quantum dots, 0210 nano-technology, Dispersion (chemistry)
Abstract

Despite their various potential applications, InAs colloidal quantum dots have attracted considerably less attention than more classical II-VI materials because of their complex syntheses that require hazardous precursors. Recently, aminophosphine has been introduced as a cheap, easy-to-use and efficient phosphorus precursor to synthesize InP quantum dots. Here, we use aminopnictogen precursors to implement a similar approach for synthesizing InAs quantum dots. We develop a two-step method based on the combination of aminoarsine as the arsenic precursor and aminophosphine as the reducing agent. This results in state-of-the-art InAs quantum dots with respect to the size dispersion and band gap range. Moreover, we present shell coating procedures that lead to InAs/ZnS(e) core/shell quantum dots that emit in the infrared region. This innovative synthesis approach can greatly facilitate the research on InAs quantum dots and may lead to synthesis protocols for a wide range of III-V quantum dots.

Published
2016
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3. Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots

Author

Ivan Infante, Pieter Geiregat, Arjan J. Houtepen, Zeger Hens, Dries Van Thourhout, Felipe Zapata, Laxmi Kishore Sagar, Christophe Delerue, Valeriia Grigel, G. Allan, Inorganic and Physical Chemistry, Universiteit Gent = Ghent University [Belgium] (UGENT), Deparment of Chemistry, Opto-electronic materials section, Delft University of Technology (TU Delft), Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratoire de chimie théorique (LCT), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Physique-IEMN (PHYSIQUE-IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Department of Information Technology (INTEC), Theoretical Chemistry, AIMMS, Physics and Chemistry of Nanostructures, Universiteit Gent = Ghent University (UGENT), Physique - IEMN (PHYSIQUE - IEMN), Photonics Research Group (INTEC), and Acknowledgements This research is funded by Ghent University (Special Research Fund BOF), BelSPo (IAP 7.35, photonics@be), EU-FP7 (Navolchi), NWO (Vidi grant, No. 723.013.002) Horizon 2020 ITN Phonsi and ERC-ULPICC and ERC-PoC Interdot. P.G. acknowledges the FWO Vlaanderen for a postdoctoral fellowship. S. Flamee is acknowledged for TEM imaging of the QDs and R. Van Deun and P. Smet are acknowledged for the use of the steady-state and time-resolved photoluminescence set-up and the cryogenic spectroscopy, respectively.

Subjects
Amplified spontaneous emission, Materials science, Infrared, LIGHT-EMITTING-DIODES, SOLIDS, Physics::Optics, 02 engineering and technology, 010402 general chemistry, Population inversion, 01 natural sciences, law.invention, Optical pumping, chemistry.chemical_compound, law, General Materials Science, Stimulated emission, SDG 7 - Affordable and Clean Energy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], SILICON, ComputingMilieux_MISCELLANEOUS, DISPLACEMENT, [PHYS]Physics [physics], business.industry, Mechanical Engineering, Mercury telluride, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Laser, 0104 chemical sciences, NANOCRYSTALS, chemistry, Physics and Astronomy, Mechanics of Materials, Quantum dot, LUMINESCENCE, Optoelectronics, PBSE, 0210 nano-technology, business
Abstract

International audience; AbstractColloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.

Published
2018
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4. The Surface Chemistry of Colloidal HgSe Nanocrystals, toward Stoichiometric Quantum Dots by Design

Author

Ivan Infante, Qiang Zhao, Valeriia Grigel, Jonathan De Roo, Kim De Nolf, Zeger Hens, Laxmi Kishore Sagar, André Vantomme, Theoretical Chemistry, and AIMMS

Subjects
General Chemical Engineering, Selenourea, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Chloride, Metal, chemistry.chemical_compound, Oleylamine, Materials Chemistry, medicine, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Crystallography, chemistry, Nanocrystal, Quantum dot, visual_art, visual_art.visual_art_medium, Density functional theory, 0210 nano-technology, SDG 6 - Clean Water and Sanitation, Stoichiometry, medicine.drug
Abstract

The prevalent structure of binary semiconductor nanocrystals is a crystallite enriched in metal cations and terminated by anionic surface species that are classified as X-type ligands. Here, we demonstrate that HgSe NCs synthesized from selenourea and mercury chloride in oleylamine have a stoichiometry close to that of bulk HgSe and feature a surface terminated by oleylammonium chloride: a combination of composition and ligand capping that preserves charge neutrality. We demonstrate that oleylammonium chloride can be formed as a side product of the formation of HgSe in the particular reaction mixture used. We complement the experimental work with a detailed investigation by density functional theory of a [HgSe]55 model system. This analysis confirms that the combination of a stoichiometric HgSe nanocrystal and alkylammonium chloride ligands forms a stable structure. Moreover, DFT predicts that stoichiometric HgSe nanocrystals prefer binding of methylammonium chloride over binding of mercury chloride. We thus conclude that HgSe NCs are retrieved with this unconventional surface termination because it is (1) possible by synthesis and (2) preferred by thermodynamics. Finally, we argue that the identification of surface ligands as acids or bases provides a convenient alternative to the covalent bond classification for describing NC-ligand binding motifs involving ion-pairs.

Published
2018
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