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Accelerating Next-Gen Materials Discovery for Photovoltaic Applications Using AI-Driven Synthesis and Characterization
No full textInternational audienceTo effectively combat climate change, we must accelerate the pace of scientific breakthroughs. Fortunately, the power of artificial intelligence (AI) has opened up new possibilities, allowing us to streamline the entire process of developing new materials, from conceptual design and synthesis to in-depth characterization and analysis. In this work, we present an automated platform that leverages AI and physics modeling for high-throughput perovskite thin-film deposition, characterization, and performance and degradation analysis. Currently under development at IPVF within the project MATCH-UP, this platform is designed to control fabrication steps, material composition, and characterization workflows, aiming to generate reproducible high-quality data for national and international collaborations. Our effort also incorporates implementing SCORE, a novel algorithm that outperforms classical optimization techniques. Typically, automated discovery relies on Bayesian optimization, which faces challenges due to the curse of dimensionality and the need for significant computational resources in high-dimensional spaces. Herein, we demonstrate how SCORE not only addresses these limitations but also excels in several solar energy challenges, offering a solution that researchers can use without needing heavy computational resources
Operando Tracking of Resistance, Thickness, and Mass of Ti3C2Tx MXene in Water‐in‐Salt Electrolyte
No full textInternational audienceMXenes are among the fastest‐growing families of 2D materials, promising for high‐rate, high‐energy energy storage applications due to their high electronic and ionic conductivity, large surface area, and reversible surface redox ability. The Ti 3 C 2 T x MXene shows a capacitive charge storage mechanism in diluted aqueous LiCl electrolyte while achieving abnormal redox‐like features in the water‐in‐salt LiCl electrolyte. Herein, various operando techniques are used to investigate changes in resistance, mass, and electrode thickness of Ti 3 C 2 T x during cycling in salt‐in‐water and water‐in‐salt LiCl electrolytes. Significant resistance variations due to interlayer space changes are recorded in the water‐in‐salt LiCl electrolyte. In both electrolytes, conductivity variations attributed to charge carrier density changes or varied inter‐sheet electron hopping barriers are detected in the capacitive areas, where no thickness variations are observed. Overall, combining those operando techniques enhances the understanding of charge storage mechanisms and facilitates the development of MXene‐based energy storage devices
Analyses of Electrode–Electrolyte Interactions in Commercial Layered Oxide/Hard Carbon Na‐Ion Cells via Optical Sensors
No full textInternational audienceMonitoring the chemical and physical processes during the initial charge of commercial‐type cells is crucial for accelerating their optimization. In this study, operando optical calorimetry, pressure sensing, and infrared fiber evanescent wave spectroscopy (IR‐FEWS) are harnessed as powerful diagnostic tools to investigate the first charge of the formation cycle of layered oxide‐based sodium‐ion cells composed of P2 or O3 cathode material and hard carbon (HC) anode. It is first revealed that the cathode composition significantly influences the initial charge behavior, showing that the O3 cathode triggers larger electrolyte decomposition than P2, which is associated with significant heat and gas generation at high states of charge. Then, the use of succinonitrile (SN) and prop‐1‐ene‐1,3‐sultone (PES) is explored as additives in the electrolyte, proving that while both additives raise the heat generation in P2/HC and O3/HC cells, they effectively suppress solvent and salt decomposition. These observations are further corroborated by online electrochemical mass spectrometry (OEMS) and X‐ray photoelectron spectroscopy (XPS) analyses. Overall, this work underlines the importance of combining operando calorimetric and chemical studies in optimizing the cell chemistry and highlights the effectiveness of optical sensing techniques for investigating the interphase formation in commercial‐type cells
Ir/Ni Metallaphotoredox Catalysis for the C(sp 3 )-H Bond α-Arylation and Alkylation of N-Alkyl N-Heterocycles
No full textInternational audienceIn this work, we report a regioselective C(sp 3 )-H bond α-arylation and alkylation of N-alkyl heterocycles (carbazoles, indoles and indazoles) using a Ir/Ni metallaphotoredox catalysis. This approach enables the direct functionalization of unactivated C(sp 3 )-H bonds at the α-position of nitrogen heterocycles, offering an efficient alternative to traditional SN2 methods and providing complementary regioselectivity to transition metal catalysis, which often results in C(sp 2 )-H bond arylation. The reaction employs [Ir(dF(CF3)ppy)2(dtbbpy)][PF6] as the photocatalyst and NiCl2(dtbbpy) as the nickel source, facilitating single-electron transfer (SET) to promote radical generation and organometallic elementary cross-coupling steps. The methodology allows the use of diverse aryl chlorides and alkenes, demonstrating broad substrate scope and high functional group tolerance. Mechanistic investigations, including radical trapping and and Stern-Volmer experiments, support a photocatalytic radical pathway. This new metallaphotoredox protocol presents a robust and atomeconomical route to synthesizing valuable N-alkyl-N-aryl heterocycles.</div
Electron Paramagnetic Resonance spectroscopy of a scheelite crystal using microwave photon counting
No full textInternational audienceCounting the microwave photons emitted by an ensemble of electron spins when they relax radiatively has recently been introduced as a sensitive new method for electron paramagnetic resonance spectroscopy at millikelvin temperatures. Here, we apply this spin fluorescence method to a scheelite crystal of CaWO4, finding some known (, , and ) and other unknown paramagnetic impurities. Investigating the zero nuclear spin isotope () transition of as a model system, we provide a quantitative analysis of the time-dependent photon counting rate following an excitation pulse, as a function of its power. The achieved signal-to-noise ratio is found to be an order of magnitude higher than the one obtained by inductively-detected Hahn echo under identical conditions. Finally, we use spin fluorescence spectroscopy at low excitation power to probe the properties of rare-earth-ions close to a metallic wire deposited on the surface; our data reveal line distortion caused by the mechanical strain imparted by the thermal contractions of the metal relative to the underlying crystal. Coherent oscillations are also observed for the most highly strained ions
Exploring the Fragmentation of Sodiated Species Involving Covalent‐Bond Cleavages for Metabolite Characterization
No full textInternational audienceABSTRACT Rationale Electrospray (ESI), the most popular desorption/ionization technique used in mass spectrometry‐based metabolomics, generates both protonated and deprotonated molecules, as well as adduct ions, sodium being the most frequent monoatomic cation entering their composition. With the spread and generalization of untargeted data‐dependent and independent tandem mass spectrometry experiments, considering product ion spectra of sodium‐containing entities appears relevant to complement fragmentation information of their protonated and deprotonated counterparts. Methods Solutions of pure standards, mainly amino and organic acids, were prepared at 1 μg/mL and injected either by direct infusion or by flow‐injection prior to ESI‐MS/MS analysis. Product ion spectra of (de)protonated and sodiated molecules were recorded both in positive and negative modes on Orbitrap instruments under both non‐resonant and resonant excitation conditions. Various normalized collision energies (NCE) were applied and the resulting collisional spectra were analyzed. Results Examination of the resulting collisional spectra clearly revealed that fragmentation of sodiated ion species may produce spectra significantly different from [M + H] + or [M − H] − . They can be highly informative and result from specific fragmentation mechanisms based on covalent bond cleavages (CBCs) compared to protonated or deprotonated molecules. These specific CBCs involving sodium retention either in product ions or in neutral losses have been investigated and seem to occur when the sodium cation is involved in an ion‐ion type interaction within the structure. Conclusions Overall, we show, using representative examples of biologically relevant metabolites, the benefits of considering MS/MS data generated from sodiated entities, in addition to [M + H] + and [M − H] − collisional data, to improve metabolite identification. The differentiation of four positional isomers is a striking illustration of the power of fragmentation information obtained with species of the [M − 2H + Na] − form. Considering the number of metabolites featuring chemical groups capable of interacting with Na + , systematic integration of these data into annotation workflows should be considered
Interlaboratory Comparison Reveals State of the Art in Microplastic Detection and Quantification Methods
No full textInternational audienceIn this study, we investigate the current accuracy of widely used microplastic (MP) detection methods through an interlaboratory comparison (ILC) involving ISO-approved techniques. The ILC was organized under the prestandardization platform of VAMAS (Versailles Project on Advanced Materials and Standards) and gathered a large number (84) of analytical laboratories across the globe. The aim of this ILC was (i) to test and to compare two thermo-analytical and three spectroscopical methods with respect to their suitability to identify and quantify microplastics in a water-soluble matrix and (ii) to test the suitability of the microplastic test materials to be used in ILCs. Two reference materials (RMs), polyethylene terephthalate (PET) and polyethylene (PE) as powders with rough size ranges between 10 and 200 μm, were used to press tablets for the ILC. The following parameters had to be assessed: polymer identity, mass fraction, particle number concentration, and particle size distribution. The reproducibility, SR, in thermo-analytical experiments ranged from 62%–117% (for PE) and 45.9%–62% (for PET). In spectroscopical experiments, the SR varied between 121% and 129% (for PE) and 64% and 70% (for PET). Tablet dissolution turned out to be a very challenging step and should be optimized. Based on the knowledge gained, development of guidance for improved tablet filtration is in progress. Further, in this study, we discuss the main sources of uncertainties that need to be considered and minimized for preparation of standardized protocols for future measurements with higher accuracy
Topochemical Synthesis of Bimetallic Silicophosphide Nanoparticles in Molten Salts
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Study and mitigation of moisture-induced degradation in SHJ modules by modifying cell structure
No full textInternational audienceSilicon heterojunction (SHJ) modules are known for their high efficiency and are expected to gain significant market share in the coming years. In terms of reliability, SHJ technology can be sensitive to moisture-induced degradation and sodium-induced degradation from sodium ions released from the glass. In these degradation mechanisms, the different layers of the SHJ cell structure could play an important role that needs to be understood. This work investigates the moisture-induced degradation in SHJ modules under damp heat (DH) by varying the cell structure with different types and thicknesses of transparent conductive oxide (TCO). Due to the migration of sodium ions, the thinner the TCO layer, the higher the degradation induced. The protective effect of dielectric capping layers is also investigated, allowing at the same time to reduce the indium consumption, which is a crucial issue for SHJ cells. These layers provide protection against degradation. Finally, a schematic model is proposed to summarize the degradation mechanisms, including the effect of cell structure on them
