The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years

In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst the low-redshift BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor of 2.51 ± 0.71 from z ∼ 0.9 to z ∼ 0.1. Through this and other comparisons, we conclude that a combination of major merging (mainly wet or mixed) and in situ star formation are the main mechanisms which build stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a factor of ∼3, while their average Sérsic index increased by ∼0.45 from z ∼ 0.9 to z ∼ 0.1, also supporting a scenario involving major merging, though some adiabatic expansion is required. These observational results are compared to both models and simulations to further explore the implications on processes which shape and evolve BCGs/MMCGs over the past ∼7 Gyr

SYNTHESIS OF ANALOGUES OF MAKALUVAMINE A

International audienceA new and efficient synthesis of tricyclic pyridoquinonoxalinone 1 an analog of Makaluvamine A and its intermediates 2 and 3 has been developed starting from 5,8-dimethoxy-4,4-dimethyl[1,2,3,4]tetrahydroquinoline 4. The synthesis was accomplished in 11 steps and 4% overall yield from commercially available 2,5-dimethoxyaniline

Hybrid polymer / metal oxide thin films for photovoltaic applications

International audienc

A blend approach to bulk heterojunction solar cells based on TiO2 nanorods and conjugated polymers

International audienc

Hybrid bulk heterojunction solar cells based on blends of TiO2 nanorods and conjugated polymers

International audienc

Hybrid solar cells from the Blend of Poly(3-hexylthiophene) and ligand-capped TiO2 nanorods.

International audienceHybrid bulk heterojunction solar cells based on nanocrystalline TiO2 (nc-TiO2) nanorods capped with trioctylphosphine oxide (TOPO) and regioregular poly(3-hexylthiophene) (P3HT) are processed from solution and characterized in order to relate the device function (optical absorption, charge separation, and transport and photovoltaic properties) to active-layer properties and device parameters. Annealing the blend films is found to greatly improve the polymer-metal oxide interaction at the nc-TiO2/ P3HT interface, resulting in a six-fold increase of the charge separation yield and improved photovoltaic device performance under simulated solar illumination. In addition, the influence of the organic ligand at the nc-TiO2 particle surface is found to be crucial for charge separation. Ligand-exchange procedures applied on the TOPO-capped nc-TiO2 nanorods with an amphiphilic ruthenium-based dye are found to further improve the charge-separation yield at the polymer-nanocrystal interface. However, the poor photocurrents generated in the hybrid blend devices, before and after ligand exchange, suggest that transport within or between nanoparticles limits performance. By comparison with other donor-acceptor bulk heterojunction systems, we conclude that charge transport in the nc-TiO2:P3HT blend films is limited by the presence of an intrinsic trap distribution mainly associated with the nc-TiO2 particles

L'origine du photo-courant dans des cellules solaires à jonction volumiques ZnO :P3HT

National audienc

Hybrid bulk heterojunction solar cells based on blends of TiO2 nanorods and P3HT.

International audienceOver the past decades, organic solar cells based on semiconducting polymers or small molecules have become a promising alternative to traditional inorganic photovoltaic devices. However, to address the intrinsic limitations of organic materials, such as charge separation yield, charge transport and durability, new strategies based on hybrid organic/inorganic materials have been explored. One such approach exploits mesoporous inorganic nanostructures as electron acceptors, which takes advantage of the potential to control the active layer structure and interface morphology through nanoparticle synthesis and processing. In this work, the potential of hybrid photovoltaics will be discussed and illustrated through a recent study of bulk heterojunction systems based on the blend of TiO2 nanorods with a conjugated polymer

Elaboration of TiO2/MWCNT (Multiwall Carbon Nanotubes) Nanocomposites by Laser Pyrolysis and Their Application in Solid State Dye Sensitized Solar Cells

International audienc