Portail HAL ENSCP
Not a member yet
9647 research outputs found
Sort by
Flexible, Transparent, and Bifacial Perovskite Solar Cells and Modules Using the Wide-Band Gap FAPbBr 3 Perovskite Absorber
No full textInternational audiencePerovskite solar cells (PSCs) offer impressive performance and flexibility thanks to their simple, lowtemperature deposition methods. Their bandgap tunability allows for a wide range of applications, transitioning from opaque to transparent devices. We present the first demonstration of flexible, bifacial PSCs using the wide bandgap FAPbBr3 perovskite. The role of optimization for both electron and hole transport layers on bifaciality, transparency, and stability have been studied. PSCs achieved a maximum power conversion efficiency (PCE) of 6.8% and 18.7% under 1-Sun and under indoor light conditions, respectively, showing up to 98% bifaciality factor and an average visible transmittance (AVT) of 55%. Additionally, P1-P2-P3 laser ablation scheme has been developed on flexible PET substrate for perovskite solar modules showing PCE of 4.7% PCE and high geometrical fill factor (97.8%). These findings highlight the potential of flexible, bifacial PSCs for diverse applications like building-integrated PV, agrivoltaics, automotive tech, wearable sensors and IoT, and more. TOC GraphicWith growing global energy demand, it is necessary to move from fossil fuels to renewable energy resources. Solar energy is a promising solution and photovoltaics technology has made significant progress in recent years. Perovskite solar cells (PSCs) have achieved impressive power conversion efficiencies (PCEs) of up to 26% in a short timeframe 1,2 . PSCs are ideal for flexible photovoltaics, as they can be deposited using simple and low-temperature solution processing methods 3-6 . Another notable characteristic of PSCs is their remarkable band-gap tunability, which can be achieved through composition engineering 7,8 . The incorporation of bromide and chloride into the perovskite composition allows for the creation of highly transparent perovskites with band gaps as high as 2.39 eV 8 . Furthermore, PSCs exhibit excellent performance in the blue-light region, making them well suited as light harvesters for diffused sunlight on cloudy days and low-intensity indoor lighting during nights 9-11 . This, combined with flexibility provide an easy installation option to seamlessly integrate PVs into surfaces such as building facades, windows and walls, sensors, electric vehicles, wearable devices, and smart displays and act as replacements for conventional energy sources 7,9,12-15 .Unlike opaque photovoltaics, ST-PVs aim to maximize both average visible transmittance (AVT) and PCE simultaneously, considering the trade-off between AVT and PCE. 14,16,17 . Consequently, a new metric, called Light Utilization Efficiency (LUE), has emerged, which represents the product of PCE and AVT 14 . LUE quantifies the potential of emergent ST-PV technologies in converting incoming visible light into electricity while maintaining rather high AVT. A suitable for applications such as smart windows, low-power displays, and automotive industry ST-PV technology should guarantee AVT greater than 50-80% 14 . The optimal bandgap range to achieve AVT values of 50-80% is typically between 2.18 and 2.32 eV 9 . Formamidinium lead bromide (FAPbBr3) perovskite, which has a band gap of 2.23 eV, falls well within the optimal band gap range for achieving high AVT, and has already demonstrated AVT values exceeding 50% 18,19 . The PCE of opaque FAPbBr3 solar cells typically reaches around 10% 20-22 . However, when using semitransparent back contact, PCE decreased to approximately 8% 18,19,23 . This reduction in efficiency is primarily attributed to the lack of back-reflection of the metallic back contact, which results in the reduced collection of backscattered light for harvesting. Furthermore, semitransparent solar cells often employ a thinner absorber layer to enhance the AVT of the cell. FAPbBr3-based semitransparent PSCs exhibit minimal angular dependence of PCE, making them highly attractive for window-integrated applications 19 . When deposited on flexible substrates, these cells also experience a decrease in PCE, with the highest reported PCE of 5.0% for flexible opaque cells 24 and no flexible semitransparent PSCs (ST-PSCs) reported using this perovskite to the best of our knowledge. In this study, we fabricated flexible, bifacial PSCs using FAPbBr3 perovskite as absorber. The devices have architecture of PET/ITO/SnO2/FAPbBr3/HTL/ITO (Figure 1a). First, we examined the impact of potassium (K) treatment on the SnO2 used as electron transport layer (ETL). Secondly, we studied the effect of hole transport layer (HTL) on the device bifaciality factor and long-term stability. Lastly, we fabricated flexible, bifacial perovskite solar modules for the first time with high geometrical fill factor of 97.8%. The fabricated flex-ST-PSCs demonstrated high bifaciality factor achieving similar PCEs from both sides.For SnO2-based PSCs, treatment with potassium ionic salts has become a very common passivation method to improve device performance 25-28 . The cations and/or anions of these salts play various roles in increasing the performance of PSCs. For example, they can passivate defects in SnO2 or perovskite layer, as well as act as preferred nuclei for perovskite formation by forming ionic bonds with perovskite precursors 25 . We performed potassium treatment to investigate its effectiveness in wide-bandgap bromide-based perovskite, FAPbBr3, using potassium chloride (KCl) salt. Figure 1b presents the statistical</div
Advanced Methods for Characterizing Battery Interfaces: Towards a Comprehensive Understanding of Interfacial Evolution in Modern Batteries
No full textInternational audienceBatteries are complex systems operating far from equilibrium, relying on intricate reactions at interfaces for performance. Understanding and optimizing these interfaces is crucial, but challenges arise due to the diverse factors influencing their development, making comprehensive characterization essential despite experimental difficulties. Recent advancements in characterization tools offer new opportunities to explore interfacial evolution, particularly in the solid electrolyte interphase (SEI).In this perspective article, leading experts in physical-chemical characterization techniques for electrochemical systems discuss the current state-of-the-art and emerging approaches to study interfaces and their evolution in batteries. The focus here is on the capabilities, technical challenges, limitations, and requirements that these techniques must meet to advance our understanding of battery interfacial evolution. The emphasis is placed on techniques that enable probing interfaces under realistic conditions, close to commercial battery systems, and on the integration of multiple approaches within a single measurement (multimodal) to minimise variable effects.This article focuses on the most promising techniques for characterizing all phases relevant to interfacial processes, as well as their integration with correlative analyses and computational modelling. We discuss solid phase characterization with X-ray spectroscopies and microscopies (XPS, XAS, STXM, X-PEEM & XCT), Raman spectroscopies (SERS, TERS & SHINERS), solid-state NMR and electron microscopies and spectroscopies (STEM, EDSX, EELS & 4D-STEM). The liquid phase characterization is discussed in terms of solution NMR spectroscopy, TEM and optical spectroscopies, while the gas phase can be characterized using OEMS, Pressure monitoring and GCMS. Computational modelling and simulation (DFT, ReaxFF & MLIP) are also discussed
Shaping, Degradation And Drug Release Of Biosourced Particles Made From Acrylated Vegetable Oils
No full textChemRxivThe widespread employment of petroleum-based polymers is the cause of unsolved environmental problems, such as the pollution by microplastics. In this context, biodegradable plastics have attracted attention as new materials that can replace conventional ones in certain applications, especially those made from renewable resources such as acrylated epoxidized soybean oil (AESO). While AESO has been shown to be used efficiently as a plasticizer or coating material, we show here that it can be used to make microparticles of simple and sophisticated shapes, including core-shell structures, using bulk shearing or microfluidic techniques. After characterizing the polymerization conditions, we show that these particles are degradable in mild chemical or enzymatic conditions, and that they can encapsulate fluorescent probes or hydrophobic molecules of therapeutic interest. Finally, we show that they can release these molecules using a well defined mechanism in simulated digestion fluids
Halogenated monopyridinium oximes are less effective in reactivation of phosphylated cholinesterases than bisquaternary oximes
No full textInternational audienceMono-quaternary pyridinium oximes derived from K-oximes K027, K048 and K203 were designed, synthesized and evaluated for the reactivation of organophosphate-inhibited cholinesterases. The incorporation of the halogen atoms to the structure decreased the pKa value of the oxime group resulting in an increased formation of oximate necessary for reactivation. The stability and pKa values were found to be similar to analogous bisquaternary compounds. Some mono-quaternary oximes resulted as relatively strong inhibitors of human acetylcholinesterase. Nevertheless, the reactivation ability of mono-quaternary oximes for organophosphateinhibited cholinesterases was lower compared to their bis-quaternary analogues. These results were further confirmed by the determination of reactivation kinetics, when in some cases novel compounds showed improvement reactivation compared to the tested standards, but no improvement to bis-quaternary K-oximes. A computational study investigated reactivation process for K027, and its two analogues for VX-inhibited AChE. This study revealed slight differences between reactivation of mono-quaternary and bis-quaternary oximes
Soft jamming of viral particles in nanopores
No full textInternational audienceViruses have remarkable physical properties and complex interactions with their environment. However, their aggregation in confined spaces remains unexplored, although this phenomenon is of paramount importance for understanding viral infectivity. Using hydrodynamical driving and optical detection, we developed a method to detect the transport of single virus in real time through synthetic nanopores. We unveiled a jamming phenomenon specifically associated with virus confinement under flow. We showed that the interactions of viral particles with themselves and with the pore surface were critical for clog formation. Based on the detailed screening of the physical and chemical determinants, we proposed a simple dynamical model that recapitulated all the experimental observations. Our results pave the way for the study of jamming phenomena in the presence of more complex interactions
Decoupling immunomodulatory properties from lipid binding in the α-pore-forming toxin Sticholysin II
No full textInternational audienceSticholysin II (StII), a pore-forming toxin from the marine anemone Stichodactyla helianthus, enhances an antigen-specific cytotoxic T lymphocyte (CTL) response when co-encapsulated in liposomes with a model antigen. This capacity does not depend exclusively on its pore-forming activity and is partially supported by its ability to activate Toll-like receptor 4 (TLR4) in dendritic cells, presumably by interacting with this receptor or by triggering signaling cascades upon binding to lipid membrane. In order to investigate whether the lipid binding capacity of StII is required for immunomodulation, we designed a mutant in which the aromatic amino acids from the interfacial binding site Trp110, Tyr111 and Trp114 were substituted by Ala. In the present work, we demonstrated that StII3A keeps the secondary structure composition and global folding of StII, while it loses its lipid binding and permeabilization abilities. Despite this, StII3A upregulates dendritic cells maturation markers, enhances an antigen-specific effector CD8+ T cells response and confers antitumor protection in a preventive scenario in C57BL/6 mice. Our results indicate that a mechanism independent of its lipid binding ability is involved in the immunomodulatory capacity of StII, pointing to StII3A as a promising candidate to improve the reliability of the Sts-based vaccine platform
Instability of Cobalt-Substituted Polyoxometalates during the Oxygen Evolution Reaction: An Operando X-ray Absorption Spectroscopy Study
No full textInternational audienceComplexes of cobalt(II) stabilized by lacunary polyoxometalates (CoPOMs) are highly discussed water oxidation catalysts (WOC). While their activity and stability in the oxygen evolution reaction (OER) have been widely explored, there is still no consensus between those claiming that CoPOMs are active and stable OER catalysts and those suggesting that they rather act as precatalysts, which degrade into OER-active heterogeneous CoOx catalysts. In this work, we use operando X-ray absorption spectroscopy along with electrochemical methods (cyclic voltammetry, chronoamperometry) to assess the activity and stability of [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16– (Co9POM) under chemical and electrochemical operating conditions. First, we demonstrate that Co9POM dissolved in a phosphate buffer quickly degrades during an electrochemical OER, leaving a Co(III)/Co(II)-containing layer on the electrode surface that acts as a heterogeneous OER catalyst. This degradation is detected using both the post mortem and operando X-ray absorption near-edge structure and extended X-ray absorption fine structure. Then, the electrochemical OER is studied in the presence of 2,2′-bipyridine, which is used to eliminate Co2+ aqua-complexes resulting from Co9POM dissociation equilibrium. Yet, this does not avoid the formation of a Co-containing precipitate, albeit of a different composition. Finally, to differentiate between degradation associated with the catalytic cycle itself and the one provoked by local pH changes in the vicinity of the electrode during the OER, the Co9POM is studied as a homogeneous WOC with NaClO as a chemical oxidant. An irreversible loss of Co from the Co9POM is detected after the addition of two NaClO equivalents per Co ion. These combined insights provide clear operando evidence of Co9POM instability under either electrochemical OER or chemical WOC operating conditions
Cellular automata modelling applied to corrosion
No full textInternational audienceThis Chapter provides an introduction to cellular automata (CA) modelling of corrosion. A brief historical presentation of CA is given, followed by CA general definition. In the context of corrosion, the CA mesoscopic modelling is compared to alternative macroscopic and microscopic approaches. The relevance of the mesoscopic CA is emphasized. CA modelling of some characteristic processes, like reaction-diffusion and passivation, are then detailed. Finally, probabilistic, synchronous/asynchronous and parallel CA algorithms are examined and some related issues pointed out
Stereoselective Synthesis of 4‐Hydroxy‐1‐Silyl‐1‐Allenylboranes and Access to 2‐Silylethynyl‐1,3‐Diols
No full textInternational audienceThe highly stereoselective gem ‐silylboration of chiral 2‐substituted 1‐ethynylepoxides is reported herein. The reaction involves first the deprotonation of the epoxides in the acetylenic position followed by transmetallation with Et3SiBpin. The transient silylborane ate‐complexes generated undergo the stereoselective 1,2‐migration of the Et3Si‐group to the sp‐hybridized terminus carbon of the ethynyl‐moiety in a stereospecific anti‐addition. The moisture‐sensitive and thermally unstable 4‐hydroxy‐1‐triethylsilyl‐1‐allenyl(pinacolato)boranes thus obtained react with aldehydes through an SE2’‐mode of addition, affording highly functionalized 2‐triethysilylethynyl‐1,3‐diols with a good diastereoselectivity which is rationalized by a Yamamoto‐Houk type transition state model
Solid-state NMR of vulcanized natural rubber / butadiene rubber blends: Local organization and cross-linking heterogeneities
No full textInternational audienceElastomer blends, among which natural rubber (NR) and butadiene rubber (BR), are involved in many components of the automotive/tire industry. A comprehensive understanding of their mechanical behavior requires, among other features, a detailed description of the cross-link density in these mixtures. In the case of vulcanized immiscible blends, the distribution of the cross-link density within each of the NR- and BR-rich domains is key information, but difficult to determine using the conventional approaches used for one-component cross-linked elastomers. In this study, the vulcanization within NR/BR blends is investigated using a robust 1H double-quantum (DQ) MAS recoupling experiment, BaBa-xy16. Two kinds of cross-linked NR/BR blends were considered with two different microstructures for the BR component. The bulk organization of the resulting blends was first probed by analyzing the 1H spin-lattice relaxation behavior. In a second step, BaBa-xy16 was used to investigate, in a selective way, the cross-link heterogeneities within NR/BR blends. In particular, for immiscible NR/BR mixtures, the distribution of the cross-link density between both phases was compared and the observed differences were discussed