Damien Garrot

Π‐Stacking Functionalization of Carbon Nanotubes through Micelle Swelling

We report on a new, original and efficient method for pi-stacking functionalization of single-wall carbon nanotubes. This method is applied to the synthesis of a high-yield light-harvesting system combining single-wall carbon nanotubes and porphyrin molecules. We developed a micelle-swelling technique that leads to controlled and stable complexes presenting an efficient energy transfer. We demonstrate the key role of the organic solvent in the functionalization mechanism. By swelling the micelles, the solvent helps the non-water-soluble porphyrins to reach the micelle core and allows a strong enhancement of the interaction between porphyrins and nanotubes. This technique opens new avenues for the functionalization of carbon nanostructures.

Quantum efficiency of energy transfer in noncovalent carbon nanotube/porphyrin compounds

We report on the quantum yield of excitation energy transfer in noncovalently bound nanotube/porphyrin compounds. Evidence for energy transfer is gained from photoluminescence excitation experiments. We perform a quantitative evaluation of the transfer quantum yield in the case of (6,5) nanotubes through three independent methods: quantitative photoluminescence excitation measurements, evaluation of the luminescence quenching of the donor (porphyrin) and ultrafast transient absorption measurements. The latter shows a tremendous increase in the porphyrin recovery rate upon incorporation in the compound. All these measurements consistently lead to an exceptional quantum yield: η∼1(10−5<1−η<10−3).

Comparison of photoluminescence properties of semiconductor quantum dots and non-blinking diamond nanoparticles and observation of the diffusion of diamond nanoparticles in cells

Long term observations of photoluminescence at the single-molecule level were until recently very difficult, due to the photobleaching of organic fluorophore molecules. Although the inorganic semiconductor nanocrystals can overcome this difficulty showing very low photobleaching yield, they suffer from photoblinking. A new marker has been recently introduced, relying on diamond nanoparticles containing photoluminescent color centers. In this work we compare the photoluminescence of single quantum dots (QDs) to the one of nanodiamonds containing a single-color center. Contrary to other markers, photoluminescent nanodiamonds present a perfect photostability and no photoblinking. At saturation of their excitation, nanodiamonds photoluminescent intensity is only three times smaller that the one of QDs. Moreover, the bright and perfectly stable photoluminescence of nanodiamonds allows wide field observations of single nanoparticles motion. We demonstrate the possibility to follow the trajectory of such single particle in cells in culture and characterize its diffusion.

Two-Dimensional Perovskite Activation with an Organic Luminophore.

A great advantage of the hybrid organic-inorganic perovskites is the chemical flexibility and the possibility of a molecular engineering of each part of the material (the inorganic part and the organic part respectively) in order to improve or add some functionalities. An adequately chosen organic luminophore has been introduced inside a lead bromide type organic-inorganic perovskite, while respecting the two-dimensional perovskite structure. A substantial increase of the brilliance of the perovskite is obtained. This activation of the perovskite luminescence by the adequate engineering of the organic part is an original approach, and is particularly interesting in the framework of the light-emitting devices such as organic light-emitting diodes (OLEDs) or lasers.

Using Low Temperature Photoluminescence Spectroscopy to Investigate CH3NH3PbI3 Hybrid Perovskite Degradation

Investigating the stability and evaluating the quality of the CH3NH3PbI3 perovskite structures is quite critical both to the design and fabrication of high-performance perovskite devices and to fundamental studies of the photophysics of the excitons. In particular, it is known that, under ambient conditions, CH3NH3PbI3 degrades producing some PbI2. We show here that low temperature Photoluminescence (PL) spectroscopy is a powerful tool to detect PbI2 traces in hybrid perovskite layers and single crystals. Because PL spectroscopy is a signal detection method on a black background, small PbI2 traces can be detected, when other methods currently used at room temperature fail. Our study highlights the extremely high stability of the single crystals compared to the thin layers and defects and grain boundaries are thought to play an important role in the degradation mechanism.

Fast growth of monocrystalline thin films of 2D layered hybrid perovskite

Hybrid organic–inorganic perovskites are on the way to deeply transforming the photovoltaic domain. Likewise, it recently appeared that this class of material has a lot of potential for other optoelectronic applications. One key aspect is to be able to synthesize monocrystalline thin films with large surface areas. Here, we report on the development of a new synthesis method for 2D hybrid organic–inorganic perovskite called “Anti-solvent Vapor-assisted Capping Crystallization”. This method allows us to grow monocrystalline thin films with a high aspect ratio in less than 30 minutes.

Time-resolved photoemission spectroscopy of electronic cooling and localization in CH3NH3PbI3 crystals

We measure the surface of

Diamond photoluminescent nanoparticles as innovative markers to study intracellular processes

{\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}

Light harvesting with non covalent carbon nanotube/porphyrin compounds

single crystals by making use of two-photon photoemission spectroscopy. Our method monitors the electronic distribution of photoexcited electrons, explicitly discriminating the initial thermalization from slower dynamical processes. The reported results disclose the fast-dissipation channels of hot carriers (0.25 ps), set an upper bound to the surface-induced recombination velocity

Time-Resolved Investigation of Excitation Energy Transfer in Carbon Nanotube–Porphyrin Compounds

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