Materials for energy and information

Thermoelectricity aims at the conversion of heat losses to electricity. We aim at improving nowadays devices to obtain better costs, reliabilities, conversion efficiencies, working temperatures, reduced sizes and weights.

Thanks to the avances of computational approaches to the electronic structure and because of the increasing complexity of thermoelectric materials, computational chemistry has become an asset in the optimization of materials.

We use density functional theory to describe the electronic structure of materials. This lead us to grasp the electronic transport properties and eventually the thermoelectric properties (Seebeck coefficient). The computation of vibrational properties sheds light on the thermal conductivity properties.

Keywords | Metal clusters, Chalcogenides, Phonons dispersion, Electronic transport, Boltzmann transport equation

People involved | Bruno Fontaine, Régis Gautier, Jean-François Halet

The conversion of solar energy to electricity, i.e. photovoltaics, plays a determinant part in accessing a carbon-free society. In order to improve the part of solar energy in the energy mix, it is of prime importance to design new absorber materials that can efficiently convert the light, while maintaining low production costs. At the same time, there is an industrial challenge in designing more efficient and less expensive light-emitting diodes (LED).

Early 2010s, a halide perovskites have shaken the world of optoelectronics thanks to (i) easy solution-processed crystal growth, and (ii) impressive power conversion efficiencies (over 25% nowadays). Thanks to a close collaboration with the teams from Institut FOTON (UMR 6082) and many experimental colleagues, we contribute to the understanding and progress of 3-dimensional and layered halide perovskites for optoelectronics and spinorbitronics applications.

Keywords | Halide perovskites, Layered structures, Exciton, Bethe-Salpeter equations, Quantum confinement, Dielectric confinement

People involved | Claudine Katan, Mikaël Kepenekian

Information and communication technologies (ICT) are at the heart of Industry 4.0 (or industry of the future), which consists of setting up intelligent factories, in which machines and products communicate with each other through a network itself connected to the outside (interconnected global system). In this context, ICT can be used for sustainable development, through Green ICT aimed at reducing the economic, ecological and social footprint of a product or service. Such advances require the optimization of current information storage devices and the invention of new concepts. Our work is at the same time on the magnetic systems, which are at the heart of current technologies, and the multiferroic materials which appear as a solution for the next generation devices.
Beyond this applied research context, our studies more generally target magnetic and / or multiferroic materials exhibiting magnetic frustration, and leading to exotic magnetic states. 

Keywords | Oxides, Mixed-anion compounds, Intermetallics, Magnetic exchange couplings, Magnetic anisotropy, DFT, Monte-Carlo simulations

People involved | Xavier Rocquefelte