2 sujets /SYMMES/STEP

Dernière mise à jour : 19-02-2018


 

Synthesis and characterization of organic photochromic dyes for application in dye sensitized solar cells with variable optical transmission

SL-DRF-18-0523

Research field : Chemistry
Location :

SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SyMMES)

Synthèse, Structure et Propriétés de Matériaux Fonctionnels (STEP)

Marcoule

Contact :

Renaud DEMADRILLE

Starting date : 01-10-2018

Contact :

Renaud DEMADRILLE

CEA - DRF/INAC/SyMMES/STEP

04 38 78 44 84

Thesis supervisor :

Renaud DEMADRILLE

CEA - DRF/INAC/SyMMES/STEP

04 38 78 44 84

Personal web page : http://inac.cea.fr/Pisp/57/renaud.demadrille.html

Laboratory link : http://inac.cea.fr/Phocea/Vie_des_labos/Ast/ast_service.php?id_unit=1147

More : http://www.spram-solar.fr/

Among the emerging photovoltaic technologies, dye-sensitized solar cells (DSSC) show some of the required features for applications and future developments at the industrial level. The SyMMES laboratory has started to develop since 2012, new purely organic dyes for the replacement of ruthenium dyes in DSSCs. Some of these new molecules have shown high performances (above 10%) and outstanding stability (more than 5000h under continuous irradiation at 65°C) when combined to ionic-liquid based electrolytes.

In this thesis project we propose to develop a new class of organic sensitizers based on functional aromatic chromophores that will confer photochromic properties to the molecules.These molecules are expected to show reversible and tunable absorption in the visible range upon irradiation. The functional aromatic heterocycles will be developed in the first part of the project and incorporated in chemical structures of push-pull type organic dyes. Using this strategy we will develop sensitizers with variable absorption bands.

In order to develop more robust and efficient solar cells, ionic liquid electrolytes containing iodine-free redox systems will be developed. Our objective will be to obtain fully transparent and stable electrolytes to give rise to a new generation of robust and efficient dye-sensitized solar cells with variable optical transmission.

Using the research facilities of Hybrid-En and the equipment that is available in SyMMES the new molecules and electrolytes will be fully characterized (structural, electrochemical, optical properties), and they will be incorporated and tested in devices. Their photovoltaic performances and their stability will be evaluated.

SiNW composites in high energy density lithium-ion batteries

SL-DRF-18-0291

Research field : Ultra-divided matter, Physical sciences for materials
Location :

SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SyMMES)

Synthèse, Structure et Propriétés de Matériaux Fonctionnels (STEP)

Marcoule

Contact :

Cédric HAON

Pascale CHENEVIER

Starting date : 01-10-2018

Contact :

Cédric HAON

CEA - DRT/DEHT//LCB

04 38 78 34 71

Thesis supervisor :

Pascale CHENEVIER

CEA - DRF/INAC/SyMMES/STEP

04 38 78 07 21

Personal web page : http://inac.cea.fr/Pisp/pascale.chenevier/

Laboratory link : http://inac.cea.fr/symmes/

More : http://liten.cea.fr/cea-tech/liten

The lithium-ion battery (LiB) technology, used for portable electronics as well as electrical vehicles, is based on continuously changing materials to improve their energy storage capacity, life span and safety. Silicon is interesting as an active material because it can absorb up to 10 times more lithium than carbon, the usual material in the negative electrode of commercial LiB. Besides silicon can be mixed with carbon in the electrode. Only silicon in the form of nanosized particles or wires can make long-standing battery electrodes, because mechanical constraints during the charge/discharge cycles induce silicon fracturing into disconnected powder. But on the other hand, nanosized silicon offers a large surface area to surface side-reactions, leading to lithium immobilization and performance loss.

In the present PhD project, two recent CEA technologies will be associated: a method for silicon nanowire growth at large scale (patents 2014-2016), and a process for making silicon-carbon composites in which nanosized silicon is embedded in carbon microparticles. The student will be in charge of material synthesis, characterization and performance tests in LiB. In order to optimize synthesis processes and LiB life span, he/she will try to understand the reactivity of all components of the composite during LiB cycling by electronic microscopy, spectroscopy and electrochemistry.

• Chemistry

• Ultra-divided matter, Physical sciences for materials

 

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