Physical modeling of charge transport
With our expertise gained from our work on nanocrystal memories, we started a short time ago the study of nanocrystals for inorganic photovoltaics, which significantly strengthens links with themes 1 and 3. On the other hand, a new activity on organic photovoltaic cells has created a close link with the theme 2. Finally, a third activity on networks of carbon nanotubes has emerged recently, it also created a new tight link with the theme "Compact modeling of advanced devices" of the team "Heterogeneous systems and microsystems." These three activities are all centered around the modeling of charge transport and consider intrinsically disordered systems.
- Inorganic nanocrystals for photovoltaics
The potential of semiconductor nanocrystals for the production of photovoltaic cells of 3rd generation looks promising. There are many models dealing with structures composed of nanocrystals. These models establish the band structures of ordered layers of nanocrystals, or consider a disordered layer as a continuum. Approaches on small disordered networks also exist, but they are not transferable to large layers. We propose to use our previous work on the effect of disorder to build more realistic band structures of disordered layers of nanocrystals. In addition, we also want to introduce the effect of dopants in the nanoparticles and thus quantify their impact on the conduction properties of the layer. These studies are complementary to the work of themes 1 and 3, as they allow to optimize the referred structures to achieve the required properties for use in photovoltaic cells.
- Organic photovoltaic cells
There are several references in the field of modeling the characteristics of cells whose photoactive layer is composed of semiconducting polymers and molecules (one-dimensional model for the diffusion / conduction of free carriers, one-dimensional model extended to a second dimension taking into account the exciton diffusion). Since we want to go beyond these models, we focus on a real and more general two-dimensional modeling that provides, in addition to the usual features, the concentrations of free carriers and excitons. Moreover, this model also allow to separate the carrier transport in their respective domains (electron in the acceptor domain, excitons and holes in the donor domain). Our goal is to contribute to a better understanding of the experimental results (theme 2) and the identification of the physical mechanisms that limit the photovoltaic performance of the considered devices. Interreg project in progress: Rhin-Solar
- Networks of carbon nanotubes
This activity originates from the ANR project "CAPTEX" started in 2010 and aims to develop a physical model of conduction in a network of carbon nanotubes. Few models exist to explain the conduction: they mainly consider the linear regime with ohmic contacts. We wish to extend the scope of these models and consider the random distribution of nanotubes within the network to be able to describe the response of the latter according to the experimental elaboration process. As the properties of carbon nanotubes derive from those of graphene, tools and models developed in the framework of the ANR "CAPTEX" should be transposed to the graphene films developed in theme 3. Such an approach should help sustain activity on carbon-based conductors, beyond the period covered by the current ANR.