Predictive design of heat management structures
Heat management is a paramount challenge in many cutting edge technologies, including new GaN electronic technology, turbine thermal coatings, resistive memories, or thermoelectrics. Further progress requires the help of accurate modeling tools that can predict the performance of new complex materials integrated in these increasingly demanding novel devices. However, there is currently no general predictive approach to tackle the complex multiscale modeling of heat flow through such nano and micro-structured systems. The state of the art, our predictive approach “ShengBTE.org”, currently covers the electronic and atomistic scales, going directly from them to predict the macroscopic thermal conductivity of homogeneous bulk materials, but it does not tackle a mesoscopic structure. This project will extend this predictive approach into the mesoscale, enabling it to fully describe thermal transport from the electronic ab initio level, through the atomistic one, all the way into the mesoscopic structure level, within a single model. The project is a 6 partner effort with complementary fields of expertise, 3 academic and 3 from industry. The widened approach will be validated against an extensive range of test case scenarios, including carefully designed experimental measurements taken during the project. The project will deliver a professional multiscale software permitting, for the first time, the prediction of heat flux through complex structured materials
of industrial interest. The performance of the modeling tool will be then demonstrated in an industrial setting, to design a new generation of substrates for power electronics based on innovating layered materials. This project is expected to have large impacts in a wide range of industrial applications, particularly in the rapidly evolving field of GaN based power electronics, and in all new technologies where thermal transport is a key issue.
Study and realization of thermal energy harvesting prototypes by thermal/fluidic coupling, and then electrical conversion. Application to electronic circuits.
The objective of this study is to explore possibilities of using systems with fluidic/thermal coupling to harvest the thermal energy released by an electronic device and then convert it into electricity that can be stored or used again. In those systems, the fluidic can be also used for a cooling purpose.
The two main steps will be the design of devices allowing controlling the operating regimes of the fluidic system submitted to a constant heat source (thermo-fluidic coupling) and the characterization of the best coupling conditions with the electrical conversion devices, in particular piezo-electrical. The studies will also explore new mechanisms taking place in the small scale fluidic systems compared to models known macroscopically. The work will be mostly experimental but will also include a simulation part.
The study should also provide an estimation of the harvesting efficiency as well as the power densities taking place in this kind of new devices.
Large-area processing and design of functional piezoelectric nanomaterials for flexible sensors and systems
CEA LETI develops innovative highly flexible strain sensors which exploit the piezoelectric properties of self-organized gallium nitride nanowires. The fabrication steps are basically: i) nanowire growth, ii) nanowire assembly, iii) encapsulation, iv) contacting. First demonstrators with small active area (1.5 cm²) have already been achieved using the Langmuir Blodgett (LB) technique for the assembly of nanowires. The present project is concerned with the scaling-up of the assembly process over large surface areas, as well as controlled patterning of nanowire assemblies in 1D and 2D by using an innovative CEA LITEN roll-to-roll technology called Boostream® which has the same functionalities as LB in its basic function.
The aim of the post doc is to develop a new building block for the Boostream® equipment enabling a controlled assembly of wires with a pre-defined design. The candidate will carry out studies to optimize the wire assembly, develop the process of film patterning and fabricate, integrate and characterize GaN nanowire piezoelectric transducers with dimensions of 15x15 cm².
More generally, this post doc will also provide the opportunity to develop a generic knowledge to manipulate micro or nano wires or fibers giving new solutions in various fields such as surface structuration, electronic skin, energy...
Kinetic study of biocide effect in nanocellulose_based food film
This project will study the kinetic of biocide effect of a nanocellulose-based film food. The main aim is to graft Ag and/or ZnO NPs on and inside halloysite particles that have a characteristic shape of twisted sheets and therefore could acting as NPs tanks. The localization of NPs outside halloysite could induce a fast biocide effect with limited duration whereas the internal grafting could produce longer biocide effect. This project gathers all steps from the film food synthesis, its nanocharacterization to the evaluation of its toxicological effect on bacteria. The final goal is to find one or many halloysite functionalizations allowing to extend the biocide effect in film food and to transpose it to other types of materials.
CIGS solar cells optimized for energy harvesting applications in indoor environments
The goal of this post-doctoral fellowship is to develop solar cells based on CIGS thin films, for energy harvesting applications (powering of small electronic autonomous devices). This research project will aim at optimizing the solar cell performances in indoor environments, i.e., under low light intensity. The post-doctoral fellow will be involved in CIGS thin film elaboration by physical vapour deposition, film characterization, solar cell realization and test.