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Investigation of Patterned Plasma Etching Processes for HJT-IBC Solar Cells: Keys to Maintaining a High Electronic Quality Surface
No full textInternational audienceWe examine a cell fabrication process involving a novel patterned plasma etching step to define the interdigitated back-contact (IBC) structure for heterojunction (HJT) crystalline silicon (c-Si) solar cells. In this process, specific plasma surface treatments are necessary to achieve good device performance. X-ray Photoelectron Spectroscopy (XPS) and High-Resolution Transmission Electron Microscopy (HRTEM) are used to investigate the underlying reasons for the effectiveness of these treatments. Two experimental conditions are explored: (1) etching the hydrogenated nanocrystalline silicon (nc-Si:H) and amorphous silicon (a-Si:H) layers down to c-Si surface before depositing the final doped layer, and (2) leaving a > 5 nm intrinsic a-Si:H (ia-Si:H) after etching. In the first case, a gentle NF3 etching step suffices to recover diode-like behavior without S-shape, but results in cells with very low open-circuit voltage (VOC). In the second case, an additional H2 plasma cleaning step is required to recover both diode-like behavior without S-shape and good minority carrier lifetime (and high VOC). XPS analysis reveals that both NF3 etching and H2 plasma can remove N, F, and O from the interface seen by the patterning plasma, although with different effectiveness for c-Si and a-Si:H surfaces. Critically, avoiding an air break between NF3 etching and H2 plasma reduces oxidation at the interface between i-a-Si:H and the final doped layer to background levels, thereby achieving the best device performance. HRTEM provides supporting insights that explain the necessity of the etching steps and the importance of stopping the etching at the i-a-Si:H layer before reaching the c-Si surface
Phenothiazine Dimer as Efficient and Recyclable p‐Type Organic Positive Electrode Material for Anion‐Ion and Dual‐Ion Batteries
No full textInternational audienceThis article presents the electrochemical properties of a series of phenothiazine and phenoxazine dimers, by involving an aromatic central core, efficiently synthesized in a single step through a Buckwald–Hartwig coupling reaction. A synergistic approach combining experimental and quantum chemical studies was used in view of providing a thorough characterization of their capabilities as electrodes in the context of electrochemical energy storage applications. A detailed study of the electrochemical activity was then conducted with the aim of optimizing performance, i.e., achieving a specific capacity of around 100 mAh.g −1 , close to the theoretical values at a potential of 3.6 V relative to Li metal. The dimerization strategy also emerged as an interesting methodology, since it gives rise to molecular materials having specific solubility properties. This finding opens up the possibility of recovering the active material from the electrode at the end of its life, thus paving the way for improved organic electrodes and batteries, especially with respect to their recyclable character
Incorporation of isolated Ag atoms and Au nanoparticles in copper nitride for selective CO electroreduction to multicarbon alcohols
No full textInternational audienceCO electroreduction has recently been explored as an alternative to CO2 electroreduction for multicarbon product formation, because it bypasses the large carbon loss associated with CO2 electroreduction. Although ethylene is generally obtained as the major product, shifting electrolysis towards the production of alcohols is an industrially promising path forward. Here we report a trimetallic-copper-based catalyst, consisting of copper nitride doped with gold nanoparticles and isolated silver atoms, with high selectivity for the formation of C2+ alcohols (Faradic efficiency for ethanol + n-propanol is >70%), within gas-fed flow cells at high current densities. Although active sites are metallic Cu(111) copper atoms derived from copper nitride, gold and silver doping suppresses ethylene formation due to the increased carbophibicity of the catalyst surface, as shown computationally. Overall, these findings open new perspectives regarding the design of catalysts for the production of liquid products from CO
Effect of PTFE Thickness on Gas Sensing Properties of TiO2/Pd-Doped ZnO Nanostructures
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Dual-site passivation by heterocycle functionalized amidinium cations toward high-performance inverted perovskite solar cells and modules
No full textInternational audiencePresently, most high-efficiency inverted perovskite solar cells (PSCs) are fabricated using toxic antisolvent and in a nitrogen-filled glovebox, which results in increased cost, reduced reproducibility, and incompatibility with large-area modules. In addition, interfacial trap-assisted nonradiative recombination impedes the further advancement of power conversion efficiency (PCE) and long-term operational stability of p–i–n inverted PSCs. Herein, we report a dual-site passivation of anionic and cationic defects through heterocycle functionalized amidinium cations, which stabilizes the interface between perovskite films and electron transport layers and minimizes interfacial nonradiative recombination loss. The dual-site passivation of amidinium cations is accomplished through precisely modulating the distance between two anchoring sites and spatial conformation. The dual-site passivation endows pyridine-functionalized amidinium salt 4-amidinopyridinium chloride (APCl) with an exceptional defect passivation ability. The APCl modulation enables high-efficiency inverted PSCs with a champion PCE of 26.83% (certified steady-state PCE of 26.32%), which is the best PCE ever reported for PSCs fabricated based on vacuum flash and in ambient air. The APCl-modulated devices could retain 95.8% of their initial performance after 2000 h of continuous maximum power point tracking. Moreover, the high-efficiency large-area module with a PCE of 19.83% (aperture area of 40.1 cm2) is obtained by this dual-site passivation technique of amidinium cations
Functional Group Engineering Stabilizing Precursor Solution and Passivating Defects for Operationally Stable and Highly Reproducible Inverted Perovskite Solar Cells
No full textInternational audienceAbstract The instability of perovskite precursor solution induced by deprotonation of organic cations and oxidation of iodide ions substantially deteriorates the reproducibility and reliability of the photovoltaic performance of perovskite solar cells (PSCs). The above decomposition reactions can be conquered via the synergistic engineering of organic functional groups. However, how spatial conformation and type of weak acid functional groups impact the stability of perovskite precursor solution remains to be investigated. Herein, it is uncovered that the position of functional groups on the benzene and the type of weak acid functional groups remarkably influence the acid dissociation constant (p K a ) and thus the stability of perovskite inks. The p K a plays a decisive role in suppressing the deprotonation of organic cations and following the amine‐cation addition‐elimination reaction. The 4‐hydrazinobenzenesulfonic acid (4‐HBSA) with the lowest p K a is optimal in stabilizing perovskite inks and mitigating nonradiative recombination through defect passivation. This breakthrough enables the inverted PSCs to deliver a power conversion efficiency (PCE) of 26.79% (certified 26.36%, the highest PCE value for PSCs prepared in ambient conditions) using vacuum flash evaporation technology. The modulated PSC could maintain 92% of its initial efficiency after 2000 h of continuous maximum power point tracking
Label‐Free Machine Learning Prediction of Chemotherapy on Tumor Spheroids Using a Microfluidics Droplet Platform
No full textInternational audienceAn integrated approach is proposed to rapidly evaluate the effects of anticancer treatments in 3D models, combining a droplet‐based microfluidic platform for spheroid formation and single‐spheroid chemotherapy application, label‐free morphological analysis, and machine learning to assess treatment response. Morphological features of spheroids, such as size and color intensity, are extracted and selected using the multivariate information‐based inductive causation algorithm, and used to train a neural network for spheroid classification into viability classes, derived from metabolic assays performed within the same platform as a benchmark. The model is tested on Ewing sarcoma cell lines and patient‐derived xenograft (PDX) cells, demonstrating robust performance across datasets. It accurately predicts spheroid viability, used to generate dose‐response curves and to determine half maximal inhibitory concentration (IC50) values comparable to traditional biochemical assays. Notably, a model trained on cell line spheroids successfully classifies PDX spheroids, highlighting its adaptability. Compared to convolutional neural network‐based approaches, this method works with smaller training datasets and provides greater interpretability by identifying key morphological features. The droplet platform further reduces cell requirements, while single‐spheroid confinement enhances classification quality. Overall, this label‐free experimental and analytical platform is confirmed as a scalable, efficient, and dynamic tool for drug screening
Polyanion-mixed off-stoichiometric alluaudites Na3−δFe2±β(PO4)y(SO4)3–y as sustainable positive electrode materials for Na-Ion batteries
No full text"ADC - Accord Couperin / American Chemical Society (2024-2026)"International audienceThe transition to renewable energy sources requires cost-effective and scalable energy storage solutions based on abundant elements, such as Na-ion batteries with sustainable positive electrode materials, based on Na, Fe, and S. The sulfate-based alluaudite Na2+2δFe2−δ(SO4)3 that exhibits excellent cycling performance inspired the investigation of mixed PO43–/SO42– polyanion-based compounds with a view to increase the phase stability of sulfates. Herein, we report on various synthesis methods, such as solid-state, mechanochemical, and ionothermal treatments, to obtain nonreported until now compositions in the mixed phosphate-sulfate iron sodium alluaudite system, using the cost-effective precursors, Na3PO4 and FeSO4. Quite surprisingly, solid-state synthesis followed in situ using the synchrotron X-ray powder diffraction technique revealed the presence of an intermediate phase closely resembling the NaSICON phase Na2.65Fe2PO4(SO4)2 along with Na6Fe(SO4)4, prior to alluaudite formation. Physicochemical investigations of the alluaudite Na2.65Fe1.9(PO4)y(SO4)3–y phase, obtained via solid-state synthesis at 450 °C, confirm that the phosphate incorporation enhanced the thermal stability while preserving promising electrochemical properties, i.e., rate capability and long-term stability with no capacity loss after 50 cycles: a reversible capacity of ≈90 mAh/g is obtained at an average discharge voltage of 3.32 V vs Na+/Na and for an electrode mass loading of 16 mg/cm2. This study proposes easy and effective synthesis approaches to obtain series of compounds and opens the perspective to explore conditions of transitions between NaSICON and alluaudite structural types
Valorisation du limonène par activation C-H
No full textInternational audienceA cause du réchauffement climatique et en particulier de l’excès de dioxyde de carbone produit par les activités humaines, il devient urgent de trouver des solutions de remplacement des ressources fossiles pour la synthèse organique. Cet article traite de l’utilisation d’hydrocarbures biosourcés, les terpènes, comme source de carbone renouvelable. Il y est question du développement d’une réaction d’activation C–H et plus particulièrement d’un couplage croisé déshydrogénant entre un terpène et un alcène pauvre en électrons par catalyse au palladium. Une étude mécanistique et une application de cette transformation en catalyse micellaire est ensuite dévoilée
Catalytic Oxygen Atom Transfer Through Photochemical and Electrochemical Activation of O<sub>2</sub> or H<sub>2</sub>O
No full textInternational audienceChemical transformations involving oxygen atom transfer (OAT) to organic substrates attract significant interest across industrial, pharmaceutical, and fundamental chemical research, including areas such as bioinorganic chemistry, catalysis, and synthetic methodology. Recent advances in electrochemical and photochemical catalysis have opened up new pathways for enabling OAT processes, particularly through the reductive activation of dioxygen or oxidative activation of water. This minireview explores emerging approaches in the field, including electrocatalytic methods leveraging bioinspired transition metal complexes, photocatalytic platforms integrating catalysts with photosensitizers, photoactive materials, or organic photocatalysts, and hybrid methodologies combining electrochemical and photochemical activation. We outline future directions for innovation, ranging from the design of functional molecular architectures and device engineering to the development of scalable technologies for industrial applications