High performance graphene for non-metallic contact in perovskite devices

Despite their many positive impacts, PV panels production face threat of sustainability of growth in terms of raw materials, energy, and environment. The PV industry is very dependent on critical raw materials and this dependence is getting worse as the production and consumption of solar panels are increasing considerably.

The main goal of this project is to develop the next generation of transparent/non-transparent conductive layers based on non- critical raw materials. These layers will be used as contact, interconnections in innovative solar panels. Guiding principle of this project is to construct competitive high quality/low-cost conductive line to replace silver contact. Due to these outstanding properties, Graphene could play an essential role in replacing critical material and enhancing electrical conductivity. This Ph-D project will be devoted to the development of low and high temperature conductive graphene inks. These inks will be designed for serigraphy, inkjet, or any suitable low-cost printing deposition techniques to print contact and interconnection. i) Inks properties in terms of composition, viscosity will be tuned. ii) The behavior of printed conductive ink will be investigated after being exposed to different stress (mechanical, temperature, moisture, electrical, light, oxygen….). iii) Finally the focus will be on conductivity characterization as a function of electrode morphology (thickness, porosity, …) and mechanical resistance. The overall aim is to optimize conductivity, mechanical resistance, and durability and finally incorporate these improvement in perovskite solar cells.

Stable tandem perovskite solar cells based on new cross-linked electron transport layers

Perovskite solar cells (PSCs) have become a trending technology in photovoltaic research due to a rapid increase in efficiency in recent years. In 2020, a record efficiency of 25.5% close from Shockley-Queisser theoretical limit of 30% was reported. Tandem solar cells offer an alternative to go beyond but stability still remains an issue.

In our project, we will bring together our complementary expertise in molecular and macromolecular syntheses, thin film morphology tuning and cell device engineering to improve the stability of highly efficient inverted perovskite cells using new electron transport layers (ETL) with high electron mobility and high stability. We will design and synthesize new n-type fullerene free semiconductors. Introduction of cross-linkable groups will lead to stabilized ETLs by thermally-induced cross-linking after film formation. The efficiency and stability of these ETLs will be finally evaluated through their incorporation in tandem configuration.

GREEN PHOTOCATALYTIC PRODUCTION OF FUEL-LIKE HYDROCARBONS USING FATTY ACID PHOTODECARBOXYLASE

A PhD position in bio-photocatalysis at the I2BC/Paris-Saclay University & BIAM/Aix Marseille University in France is available for a dynamic and enthusiastic candidate. Funded by the French National Research Agency (ANR), the interdisciplinary project focuses on developing innovative biocatalysts for photo-production of hydrocarbon fuels of non-fossil origin.
The PhD project, entitled 'Green photocatalytic production of fuel-like hydrocarbons using Fatty Acid Photodecarboxylase,' aims to optimize the natural Fatty Acid Photodecarboxylase (FAP) enzyme for higher photostability and more efficient binding and photodecarboxylation of short fatty acid substrates, yielding liquid hydrocarbons.
Key responsibilities include preparing wild-type and mutant FAP proteins, conducting screening and tests of photoenzymatic activity, participating in enzyme evolution, characterizing new mutants using spectroscopic techniques, contributing to data analysis, writing scientific publications, and presenting results at conferences.
Requirements for applicants include a Master’s or engineering degree in relevant fields, practical laboratory skills, ability to work independently, proficiency in English and/or French, and readiness to relocate from Provence to Ile-de-France during the PhD.
The position offers the opportunity to contribute to sustainable energy research while gaining expertise in molecular biology, biochemistry, and optical spectroscopy. The PhD will be conducted within a collaborative ANR project involving four teams with diverse expertise and skills. The ideal candidate should integrate seamlessly into a multidisciplinary environment.
Supervisor will be Pavel Müller (pavel.muller@i2bc.paris-saclay.fr) and co-supervisor will be Damien Sorigué (damien.sorigue@cea.fr).Workplaces include the Institute of Biosciences and Biotechnologies of Aix-Marseille and CEA Saclay/Institut de Biologie Intégrative dela Cellule.
The contract begins between October 2024 and February 2025 and lasts for three years, with a monthly salary of 2400 € (brut). Applicants passionate about addressing energy challenges are encouraged to apply!

Durable radially polatised tubular nanoreactors for catalysis

Rising energy demand and the need to reduce the use of fossil fuels to limit global warming have created an urgent need for clean energy collection technologies. One interesting solution is to use solar energy to produce fuels. Low-cost materials such as semiconductors have been the focus of numerous studies for photocatalytic reactions. Among them, 1D nanostructures are promising because of their interesting properties (high and accessible specific surface areas, confined environments, long-distance electron transport and facilitated charge separation). Imogolite, a natural hollow nanotubes clay, belongs to this category. Its particularity does not lies in its chemical composition (Al, O and Si) but in its intrinsic curvature, which induces a permanent polarization of the wall, effectively separating photo-induced charges. This nanotube belongs to a family sharing the same local structure with different curved morphologies (nanosphere and nanotile). In addition, several modifications of these materials are possible (coupling with metal nanoparticles, functionalization of the internal cavity), enabling their properties to be modulated. These materials are therefore good candidates as nanoreactors for photocatalytic reactions. So far, proof of concept (i.e. nanoreactor for photocatalytic reactions) has only been obtained for the nanotube form. The aim of this thesis is therefore to study the whole family (nanotube, nanosphere and nanotile, with various functionalizations) as nanoreactors for proton and CO2 reduction reactions triggered under illumination.

Olfactory technology (Qi - Wei): Chinese inspiration for ecotechnology

The specificity of Chinese technological thought has been the subject of recurrent philosophical debate since the early 20th century. This discussion highlights the originality of the sensory relationship with nature expressed in Chinese writing and culture. “Olfactory technology (Qi - Wei): a Chinese inspiration for ecotechnology” explores the hypothesis that a philosophy of technology, inspired by China but open to other cultures, can renew thinking on technology in its relationship to the environment, based on the paradigm of olfaction (Wei).
This approach is based on an analysis of traditional Chinese thought developed by contemporary Chinese philosophers, in particular Gong Huanan, and shows its influence on current Chinese technological thought. It also draws on the work of specialists in olfaction, as well as Western philosophers of technology, science and the imaginary (such as Gilbert Simondon, Gaston Bachelard and Dominique Lestel).
The primary scientific challenge is to restore the olfactory paradigm of Chinese technological thought in order to examine its relationship to the environment, and then to develop a transcultural ecotechnological reflection. In the light of these analyses, we will then reconsider the imaginaries of robotic and digital technologies in order to explore new avenues of innovation. Finally, from a science fiction prototyping perspective, speculative fictions will extend the analysis by examining the impact of imaginable technologies based on the olfactory paradigm.

LIGHT-NMR: A POWERFUL TOOL FOR UNDERSTANDING AND IMPROVING THE PROPERTIES OF PHOTOSWITCHABLE FLUORESCENT PROTEINS

The recruited student will investigate the photophysical mechanisms of reversibly photoswitchable fluorescent proteins (RSFPs) employing solution NMR spectroscopy coupled with in-situ illumination and variable oxygen pressure. RSFPs are capable to switch between a fluorescent on-state and a nonfluorescent off-state under specific light illumination, and have fostered many types of imaging applications including super-resolution methods. Multidimensional NMR spectroscopy is a particularly powerful atomic resolution technique providing detailed information on conformational protein dynamics, as well as the local chemistry (protonation states, H-bonding interactions, …) involved in the photophysics of the chomophore within the protein scaffold. In the proposed PhD project, we intend to further improve our NMR in-situ illumination device by adding capabilities such as additional wavelengths of emitting light sources, fluorescence detection, and oxygen pressure control. This will allow to directly correlate the conformational dynamics of various states with their photophysical properties, as well as the effect of oxygen on triplet state formation and photobleaching. We will apply this NMR methodology to several green and red model RSFPs, as well as FAST systems. The goal will be to contribute fundamental knowledge of these fluorescent markers and to design improved variants.

Understanding reversibly switchable red fluorescent proteins

Fluorescence imaging is essential to unlocking the secrets of life and has benefited greatly from the discovery of fluorescent proteins (FPs). Reversibly switchable fluorescent proteins (RSFPs, https://doi.org/10.1002/iub.1023) are capable of switching from a fluorescent "on-state" to a non-fluorescent "off-state" upon specific illumination, and have fostered many imaging applications, including some super-resolution methods. However, RSFPs are still imperfect: for example, their brightness is limited, their switching kinetics is dependent on environmental conditions, their resistance to irreversible photobleaching is insufficient. In particular, whereas green RSFPs are performing relatively well, red RSFPs have been lagging behind. The switching performances of green and red RSFPs are linked with their intrinsic or light-activated protein-dynamics properties and can be studied by combining structural biology approaches, such as kinetic X-ray crystallography, with optical spectroscopy and fluorescence imaging (doi: 10.1038/s41592-019-0462-3). In the proposed PhD project, those techniques will be used to better understand red RSFPs and facilitate their rational engineering towards brighter and more photo-resistant variants. The recruited student will work in close collaboration with another PhD student to be hired, who will approach the same questions by employing NMR.

Candidates should have a strong interest to work at the interface between physics, chemistry and biology. Knowledge of advanced fluorescence microscopy and/or X-ray crystallography is required. Preliminary experience in image analysis, biochemistry, cell biology and/or molecular biology will be appreciated.

Imagerie de la compartimentation et de la pharmacologie du lithium par IRM du Lithium-7 in vivo at très haut champ magnétique.

At ultra-high magnetic field, increased polarization opens the way for the NMR imaging and spectroscopy of exotic nuclei such as Lithium-7 (7Li) and Sodium-23 (23Na) with unprecedented sensitivities.
During this PhD thesis, the goal will be to develop, validate and apply 23Na and 7Li preclinical imaging protocols in the context of the new 11.7T Iseult MRI scanner of NeuroSpin (CEA/DRF/JOLIOT) as well as on its 17.2 T preclinical scanner. The PhD student will continue the work realized these last years on 23Na and 7Li imaging and will push for better and more significant NRM data. Our focus will be to use these methods to study the pharmacology and biophysical properties of Lithium in the brain. In particular, we aim at investigating the transport kinetics of Li+ through the Blood-Brain-Barrier, its compartmentation and its competition with Na+ ions.

Compact source of electrons-positrons/muons-antimuons pairs

### Context
The context of this PhD thesis deals with laser plasma electron accelerators (LPA), which can be obtained by focusing a high-power laser into a gas medium. At focus, the laser field is so intense that it quasi-instantly ionizes matter into an undersense plasma, in which it can propagate. During laser propagation, the ponderomotive laser pressure expels plasma electrons from its path, forming a cavity void of electrons in its wake. This cavity, called ‘bubble’, can sustain accelerating fields (100GV/m) that are roughly three orders of magnitude larger than what can be provided by Radiofrequency cavities, which equip the current generation of conventional accelerators. These accelerating structures can trap some plasma electrons and accelerate them at relativistic energies (few GeVs) over distances of a few centimeters. This offers the prospect of producing much more compact and affordable accelerators, with the following goals: (i) democratizing their usage for existing applications currently reserved to only a few installations in the world (ii) enabling new applications in strategic sectors (fundamental research, industry, medicine, defense).

Among the applications for which a strong international competition exist we remark:

> The usage of these accelerators to provide the first high-energy (100 MeV) electron radiotherapy machine for medical treatmes

> The usage of these accelerators as a building block of a future large scale TeV electron/positron collider for high-energy physics

> The usage of these accelerators to develop a compact and mobile relativistic muon source to perform active muon tomography. Such a tool would be a major asset for industrial applications (e.g., safety diagnostic of nuclear reactors), and for defense applications (non-proliferation). It is worth to mention that in these two sectors the american agency DARPA has already funded an ambitious program ( Muons for Science and Security, MuS2) in 2022, with the aim of providing a first conceptual report of a relativistic moun source based on a plasma accelerator (cf. https://www.darpa.mil/news-events/2022-07-22).

### Challenges:

In order to enable the aforementioned applications, strong limitations of current laser-plasma accelerators need to be addressed. An important limitation is the low amount of charge at high-energies (100 MeV – few GeV) provided by these accelerators. The main reason behind the low accelerated charge is the fact that present-day injection techniques are based on the injection of electrons from the gas, whose density is very low. In order to address this limitation, we have recently proposed a new injection concept based on a remarkable physical system called “plasma-mirror”. This concept relies on the use of a hybrid solid-gas target. When impinging on such a target, the high-power laser fully ionizes the solid and the gas. The solid part is so dense that it can reflect the incident laser, forming a so-called ‘plasma mirror’. In the gas part, the laser propagates and drives a LPA. Upon reflection on the plasma mirror, ultra-dense electron bunches can be highly-precisely injected into the bubble of the LPA formed by the reflected laser field. As the solid offers orders of magnitude more charge than the gas medium and as charge is injected from a highly-localized region from the plasma (plane), it has the potential to level up the injected charge in LPAs while keeping a high electron beam quality.

The PHI group is an international leader in the study and control of these systems. In collaboration with LOA, by using a 100TW-class laser, we have demonstrated that this new concept allows for a significant increase of the accelerated charge while preserving the quality of the beam.

### Goals

The first objective of this PhD thesis will be to develop a multi-GeV laser-plasma accelerator based on a plasma-mirror injection on Petawatt-class laser installations like the APOLLON laser facility. With a Petawatt-class laser this accelerator should produce electrons beams at 4 GeV with a total charge of hundreds of pC and a few % energy spread. Such a beam quality would represent a substantial progress in the domain.

The second objective will be to send this electron beam into a high-Z converter in order to generate muons/anti-muons pairs. Our estimations show that we could obtain roughly 10^4 relativistic muons per shot, which would allow for the radiography of a high-Z material in a few minutes.

This PhD subject foresees:
> Theoretical/numerical modeling activities based on our exascale code WarpX (to model the laser-plasma accelerator) and on the Geant4 code (for the modeling of the high-Z converter).

> Experimental activities (high-intensity laser-plasma interaction, detection of relativistic muons)

The project involves several partner laboratories:

> The Laboratoire d’Optique Appliquée for the laser-plasma acceleration activities (A. Leblanc)

> The Lawrence Berkeley National Lab for code development activities (WarpX, J.L Vay)

> The CEA-IRFU for the detection part (micromegas technology, O. Limousin)

For the experimental part, we will use several laser facilities:

> The UHI100 laser installation for the setup and testing of the laser-plasma accelerator at reduced power

> The APOLLON installation for the setup and testing of the plasma accelerator with a PW-class laser. A first experience implementing the concept of a plasma-mirror injector at the PW-level is scheduled for May 2024 in the framework of a collaboration between CEA and LOA. Following this experiment, we will perform a second experiment (2025-2026) to generate muons on APOLLON or other laser facilities in Europe (e.g., the ELI installations).

Electrical polarisation mapping in ferroelectric devices at the nanoscale

Ferroelectric materials, with their high dielectric constant and spontaneous polarisation, are the subject of intense research in microelectronics. Polarisation is an essential parameter for these materials while its characterization remains mainly limited to the macroscopic scale by conventional electrical methods. To deepen the understanding of these materials, particularly in thin layers, and built new devices, local measurements are essential. This thesis project aims to develop a new methodology to directly map polarisation in devices at nanoscale. By combining the expertise of SPEC in thin film growth and of C2N in nanostructuration and electric measurements, we will elaborate and design a particular geometry of nanostructures allowing the use of operando electronic holography (collaboration with CEMES-CNRS, ANR POLARYS) to quantitatively map the local electrical potential in nanodevices upon application of a voltage.

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