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Séminaires

Materials for Sustainable Growth : OrganoSulfur and Sulfur Hybrids

Kookheon Char The National Creative Research Initiative Center for Intelligent Hybrids The WCU Program of Chemical Convergence for Energy & Environment School of Chemical & Biological Engineering Seoul National University

CHAIRE TOTAL ESPCI Jeudi 4 mai 2017 - 14h00 - Amphi Boreau

 

With ever-increasing human population, depleting natural resources, and rapid climate change confronting humanity, the role of chemistry is becoming more crucial in addressing these issues and establishing systems for sustainable growth. In this Seminar, recent efforts in our research center (National CRI Center for Intelligent Hybrids), utilizing both organic and inorganic material design and synthesis, to address key issues to such an end are described. As an example, we have established novel chemical methods for the direct utilization of elemental sulfur. More than seven million tons of elemental sulfur are produced in excess each year and are stockpiled in landfill-like deposits in remote areas. While elemental sulfur is known to be environmentally benign and have many interesting physical properties, the shear volume of it left unused is a major emerging issue in the petrochemical industry. Useful conversion of industrial wastes into functional materials, through novel chemistry, for key applications such as Nexgen Li-sulfur batteries and thermal IR imaging will be introduced.

Semiconductor Nanocrystals for Optoelectronics : Shape Matters for the Photon-Electron Interconversions

Kookheon Char The National Creative Research Initiative Center for Intelligent Hybrids The WCU Program of Chemical Convergence for Energy & Environment School of Chemical & Biological Engineering Seoul National University

CHAIRE TOTAL ESPCI Mercredi 10 mai 2017 - 11h00 - Amphi Boreau

 

Ever since the synthetic methodology to prepare well-defined semiconductor nanocrystals (NCs) is well-established, multilateral efforts have recently emerged to utilize such NCs for optoelectronic devices. The unique optical and electronic properties of the semiconductor NCs serve a novel funtional toolbox which has never been found in conventional technologies and it would contribute to realize more efficient, high-performance, and economic nano- or opto-electronics. To take full advantage of such promising nanomaterials, understanding the fundamental properties of semiconductor NCs along with manipulating them through rational materials design is critically important.

From the viewpoint of materials science, the fundamental design principle of semiconductor NCs and their utilization to electron-photon interconversion devices will be addressed in this presentation. For the efficient electron-to-photon conversion devices, spherical core@shell quantum dots (QDs) have been designed and utilized as the active materials in light emitting diodes (QLEDs). On the basis of the energy-tuned inverted device structure, the core@shell QDs yield color-saturated electroluminescence spectra with high external quantum efficiency and extended device lifetime. For the conversion from photons to electrons, well-defined CdSe tetrapods have been prepared by the continuous precursor injection (CPI) approach. The bicontinuous heterojunction morphology consisting of CdSe tetrapods and conducting polymers produced high photocurrent and power conversion efficiency by the effective dissociation of excitons at the interfaces. The enhancement in the field-effect mobility of CdSe tetrapod networks also suggested that such branced nanocrystals could be one of promising building blocks in hybrid solar cells.

Assembly of optically resonating colloids for the fabrication of metamaterials

Virgine Ponsinet Centre de Recherche Paul Pascal CNRS-Université de Bordeaux

Jeudi 11 mai 2017 - 14h00 - Amphi Boreau

 

I will present our recent results on the assembly of plasmonic nanoparticles into dense uniform 3D structures, in which tailored localized surface plasmon resonances of the nanoparticles provide specific optical responses. Such self-assembled metamaterials provide a promising platform towards bulk optical materials with unusual effective properties. In particular, we produce lamellar metal-dielectric nanocomposites, which constitute self-assembled hyperbolic metamaterials, and colloidal nanoresonators ("plasmonic raspberries") presenting optical magnetism at visible wavelengths, which can be assembled into a bulk magnetic metamaterial.


Interfacial effects in fluid-particles systems

Alban Sauret Surfaces du Verre et Interfaces, UMR 125 CNRS/Saint-Gobain, aubervilliers

Jeudi 20 avril 2017

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Morphing soft structures with instabilities

Joël Marthelot Elasticity, Geometry and Statistics Laboratory, MIT, Cambridge

Jeudi 6 avril 2017

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