A5030103774- Carbon Nanotubes in Composites
- Perovskite Materials and Applications
- Graphene research and applications
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- Porphyrin and Phthalocyanine Chemistry
- Strong Light-Matter Interactions
- Conducting polymers and applications
- Fullerene Chemistry and Applications
- Photonic and Optical Devices
- Nanotechnology research and applications
- Boron and Carbon Nanomaterials Research
- Graphene and Nanomaterials Applications
- 2D Materials and Applications
- Carbon and Quantum Dots Applications
- Solid-state spectroscopy and crystallography
- Thermal Radiation and Cooling Technologies
- X-ray Diffraction in Crystallography
- Quantum Dots Synthesis And Properties
- Crystallization and Solubility Studies
- Organic Light-Emitting Diodes Research
- Advanced Fiber Laser Technologies
- Diamond and Carbon-based Materials Research
- Force Microscopy Techniques and Applications
- Luminescence and Fluorescent Materials
Centre National de la Recherche Scientifique
2015-2024
Université Paris-Saclay
2016-2024
CentraleSupélec
2020-2024
Lumibird (France)
2024
Laboratoire Lumière, Matière et Interfaces
2019-2023
École Normale Supérieure - PSL
2004-2021
Laboratoire Aimé Cotton
2013-2020
École Normale Supérieure Paris-Saclay
2010-2019
Université Paris-Sud
2013-2019
École Normale Supérieure
2019
The performance of hybrid organic perovskite (HOP) for solar energy conversion is driving a renewed interest in their light emitting properties. recent observation broad visible emission layered HOP highlights potential as white-light emitters. Improvement the efficiency material requires better understanding its photophysical We present in-depth experimental investigations (WL) thin films (C6H11NH3)2PbBr4. broadband, strongly Stokes shifted presents maximum at 90 K when excited 3.815 eV,...
Optical transitions in single-wall boron nitride nanotubes are investigated by means of optical absorption spectroscopy. Three lines observed. Two them (at 4.45 and 5.5 eV) result from the quantification involved rolling up hexagonal (h-BN) sheet. The nature these is discussed, two interpretations proposed. A comparison with carbon leads one to interpret as between pairs van Hove singularities one-dimensional density states nanotubes. But confinement energy due h-BN sheet cannot explain a...
Cathodoluminescence and photoluminescence spectroscopies have been performed on hexagonal boron nitride powders. The combination of these techniques allows us to analyze the two observed luminescence bands. A deep-level UV emission at about $4\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ is attributed defects or impurities, a near-band-gap $5.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. band composed four peaks, which are phonon replica due localized vibrations. In region, six components between 5.2...
Negatively curved nanographene (NG) 4, having two heptagons and a [5]helicene, was unexpectedly obtained by aryl rearrangement stepwise cyclodehydrogenations. X-ray crystallography confirmed the saddle-shaped structures of intermediate 3 NG 4. The favorability over helicene formation following radical cation or arenium mechanisms is supported theoretical calculations. 4 demonstrates reversible mechanochromic color change solid-state emission, presumably benefiting from its loose crystal...
We focus here our attention on a particular family of 2D-layered and 3D hybrid perovskite molecular crystals, the mixed perovskites (C6H5–C2H4–NH3)2PbZ4(1–x)Y4x (CH3–NH3)PbZ3(1–x)Y3x, where Z Y are halogen ions such as I, Br, Cl. Studying experimentally disorder-induced effects optical properties 2D layered materials, we demonstrate that they can be considered pseudobinary alloys, exactly like Ga1–xAlxAs, Cd1–xHgxTe inorganic semiconductors, or previously reported compounds. afford similar...
In the field of condensed matter, graphene plays a central role as an emerging material for nanoelectronics. Nevertheless, is semimetal, which constitutes severe limitation some future applications. Therefore, lot efforts are being made to develop semiconductor materials whose structure compatible with lattice. this perspective, little pieces represent promising alternative. particular, their electronic, optical and spin properties can be in principle controlled by designing size, shape...
The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode fiber microcavity using built-in spatial and spectral matching brought by this flexible geometry. A thorough cw time-resolved investigation very same emitter both in free space cavity shows an efficient funneling into together with strong enhancement corresponding Purcell factor up 5. At time, emitted photons retain sub-Poissonian statistics. By exploiting feeding effect on phonon wings, we...
Recently, Ruddlesden–Popper 2D perovskite (RPP) solar cells and light-emitting diodes (LEDs) have shown promising efficiencies improved stability in comparison to 3D halide perovskites. Here, the exciton recombination dynamics is investigated at room temperature pure-phase RPP crystals (C6H5C2H4NH3)2(CH3NH3)n−1PbnI3n+1 (n = 1, 2, 3, 4) by time-resolved photoluminescence (TRPL) a large range of power excitations. As number layers increases, we detect presence an increasing fraction...
Hybrid perovskite thin films have demonstrated impressive performance for solar energy conversion and optoelectronic applications. However, further progress will benefit from a better knowledge of the intrinsic photophysics materials. Here, temperature-dependent emission properties CH3NH3PbI3 single crystals are investigated compared to those polycrystalline by means steady-state time-resolved photoluminescence spectroscopy. Single present sharp excitonic at high energy, with full width half...
Understanding the surface properties of organic-inorganic lead-based perovskites is high importance to improve device's performance. Here, we have investigated differences between and bulk optical CH3NH3PbBr3 single crystals. Depth-resolved cathodoluminescence was used probe near-surface region on a depth few microns. In addition, studied transmitted luminescence through thicknesses 50 600 μm. both experiments, expected spectral shift due reabsorption effect has been precisely calculated. We...
The authors have realized a Pérot-Fabry microcavity containing two-dimensional layered perovskite-type semiconductor, (C6H5C2H4–NH3)2PbI4, between dielectric mirror and metallic mirror. A strong coupling regime the perovskite exciton confined photon mode has been evidenced at room temperature from angular-resolved reflectivity experiments. An anticrossing of 140meV is observed excitonic cavity modes. (C6H5C2H4–NH3)2PbI4 having self-organized multiple quantum well structure, they determined...
The far-field emission of two-dimensional stadium-shaped microlasers is investigated. Stadium-shaped microcavities based on a laser dye embedded in polymer matrix have been elaborated. Such microresonators, made by lithography and reactive ion etching displayed quality factors greater than 6000 high output power. highly directional pattern the emitted beam (full width at half maximum ∼15°) reflects symmetries stadium shape.
This paper presents some of the particularities strong coupling regime occurring between surface plasmon (SP) modes and excitons. Two different active materials were deposited on a silver film: cyanine dye J-aggregate, two-dimensional layered perovskite-type semiconductor. The dispersion relations, which are deduced from angular resolved reflectometry spectra, present an anticrossing characteristic regime. wavevector is good parameter to determine Rabi splitting. Due large interaction...
This article reviews the synthesis, structural and optical characterizations of some novel luminescent two dimensional organic-inorganic perovskite (2DOIP) semiconductors. These 2DOIP semiconductors show a self-assembled nano-layered structure, having electronic structure multi-quantum wells. thin layers nanoparticles have been prepared through different methods. The structures are characterized by atomic force microscopy X-ray diffraction. properties theb DOIP from absorption...
Hybrid organic–inorganic perovskites are on the way to deeply transforming photovoltaic domain. Likewise, it recently appeared that this class of material has a lot potential for other optoelectronic applications. One key aspect is be able synthesize monocrystalline thin films with large surface areas. Here, we report development new synthesis method 2D hybrid perovskite called "Anti-solvent Vapor-assisted Capping Crystallization". This allows us grow high ratio in less than 30 minutes.
We analyze the behavior of a series newly synthesized (R-NH3)2PbX4 perovskites and, in particular, discuss possible reasons which cause their degradation under UV illumination. Experimental results show that process depends lot on molecular components: not only inorganic part, but also chemical structure organic moieties play an important role bleaching and photo-chemical reaction processes tend to destroy luminescent framework. In addition, we find spatial arrangement crystal influences...
Among organic electronic materials, graphene nanoribbons (GNRs) offer extraordinary versatility as next-generation semiconducting materials for nanoelectronics and optoelectronics due to their tunable properties, including charge-carrier mobility, optical absorption, bandgap, which are uniquely defined by chemical structures. Although planar GNRs have been predominantly considered until now, nonplanarity can be an additional parameter modulate properties without changing the aromatic core....
We present evidence of near-infrared photoluminescence (PL) signature nitrogen vacancy centers ${({\mathrm{N}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}})}^{\ensuremath{-}}$ in silicon carbide (SiC). This center exhibits an $S=1$ ground state spin similar to the ${\mathrm{NV}}^{\ensuremath{-}}$ diamond. have performed excitation measurements at cryogenic temperature and demonstrated efficient photoexcitation distinct from $({\mathrm{N}}_{\mathrm{C}}{\mathrm{V}}_{\mathrm{Si}}{)}^{\ensuremath{-}}$...
The excitonic recombinations in hexagonal boron nitride (hBN) are investigated with spatially resolved cathodoluminescence spectroscopy the ultraviolet range. Cathodoluminescence images of an individual hBN crystallite reveals that 215 nm free line is quite homogeneously emitted along crystallite, whereas 220 and 227 emissions located specific regions crystallite. Transmission electron microscopy show these contain a high density crystalline defects. This suggests both produced by...
We have realized Perot–Fabry microcavities containing a two-dimensional layered perovskite-type semiconductor: (C6H5C2H4–NH3)2PbI4 between dielectric mirror and metallic mirror. A strong coupling regime the perovskite exciton confined photon mode has been evidenced at room temperature from angular-resolved reflectivity experiments, anticrossings as large 190 meV are observed excitonic cavity modes. shown that design of microcavity can be varied will, so detuning or Rabi splitting precisely...
Individual multiwall boron nitride nanotubes with diameters from 30 nm to 110 are shown be efficient UV emitters by cathodoluminescence. Their luminescence does not evolve much in this diameter range, dominant recombinations at about 230 nm. As a result, single nanotube properties can obtained experiments performed on ensembles of nanotubes. Such studied photoluminescence as function temperature (5 K--300 K) and excitation 9 K. The results discussed compared the related bulk material,...
Dielectric microcavities are widely used as laser resonators and characterizations of their spectra interest for various applications. We experimentally investigate microlasers simple shapes (Fabry-Perot, square, pentagon, disk). Their lasing consist mainly almost equidistant peaks the distance between reveals length a quantized periodic orbit. To measure this with good precision, it is necessary to take into account different sources refractive index dispersion. Our experimental numerical...
We characterize strongly coupled microcavities in which optical hybridization occurs between the organic-dye zinc tetraphenyl-porphrin (ZnTPP) and a thin film of self-assembled perovskite. Position-resolved reflectivity measurements demonstrate formation hybrid organic-inorganic exciton polaritons corresponding to three-way admixture cavity photon with electronic transitions ZnTPP find that such hybrid-polariton states can undergo radiative emission, despite existence competing decay channel...