Publications

2021

• Tisagenlecleucel in adult relapsed or refractory follicular lymphoma: the phase 2 ELARA trial
  
  • Fowler Nathan Hale
  • Dickinson Michael
  • Dreyling Martin
  • Martinez-Lopez Joaquin
  • Kolstad Arne
  • Butler Jason
  • Ghosh Monalisa
  • Popplewell Leslie
  • Chavez Julio
  • Bachy Emmanuel
  • Kato Koji
  • Harigae Hideo
  • Kersten Marie José
  • Andreadis Charalambos
  • Riedell Peter
  • Ho P. Joy
  • Pérez-Simón José Antonio
  • Chen Andy
  • Nastoupil Loretta
  • von Tresckow Bastian
  • Ferreri Andrés José María
  • Teshima Takanori
  • Patten Piers
  • Mcguirk Joseph
  • Petzer Andreas
  • Offner Fritz
  • Viardot Andreas
  • Zinzani Pier Luigi
  • Malladi Ram
  • Zia Aiesha
  • Awasthi Rakesh
  • Masood Aisha
  • Anak Oezlem
  • Schuster Stephen
  • Thieblemont Catherine
  Nature Medicine, Nature Publishing Group, 2021, 28 (2), pp.325-332. (10.1038/s41591-021-01622-0)
  DOI : 10.1038/s41591-021-01622-0
• Ink-jet printed carbon nanotube based transistors as water quality sensors
  
  • Cho Gookbin
  , 2021. Over the past decades, rapid population growth and unsustainable water use in agriculture and industry have brought about hydric stress worldwide. While the demand of freshwater increases, its quality decreases. Water quality monitoring is essential to solve this world-wide water crisis, so water quality sensors have been studied extensively.Among various nanomaterials integrated to these sensors to reduce cost and increase sensitivity and selectivity, carbon nanotube (CNT) sensors are very promising due to their remarkable physical, chemical and electrical properties. The dissertation thus includes a quantitative comparison of the state of the art of CNT sensors in water across 90 references and 20 analytes.Based on this review, Carbon nanotube-based field-effect transistors (CNT-FET) appear just as promising to achieve extremely low detection limit as electrochemical sensors, but have been studied much less.After discussing the various options for design, fabrication and operating mechanisms available so far for CNT-FETs, we detail the design and fabrication process used in this work. Bottom-gated CNTFET are fabricated by ink-jet printing unsorted single-walled carbon nanotubes (SWCNTs) dispersed in 1-methyl-2-pyrrolidinone (NMP)). The SWCNT are either non functionalized (p-CNT FET) or functionalized non covalently a custom-developed conjugated polymer (FF-UR). FF-UR has a fluorene backbone, the fluorene moieties being functionalized either with two alkyle chains or with two identical sensing moieties, a urea group NH-CO-NH between two phenyl groups.The resulting CNTFETs have Ion/Ioff ratio in air between 2 and 12 for p-CNTFET and between 50 and 500 for f-CNTFET. The CNTFETs are then passivated with porous PMMA to prevent degradation and CNT loss in water. The PMMA layer also improves the Ion/Ioff of the transistors in air, by more than one order of magnitude forp-CNTFET and by about 2 for f-CNTFET.After developing a characterization protocol for CNT-FET in water, we demonstrate high pH sensitivity with both FET types (p- and f-) in phosphate and borate buffer solution. p-type behavior is observed in the case of p-CNT FETs, whereas ambipolarity is observed in the case of f-CNT FETs, with the Dirac point at the gate voltage of -0.1 V.p-CNT FETs show pH sensitivity of 25 % per pH between pH 3 to pH 9 in PBS, while f-CNT FETs show significantly higher pH sensitivity 328 %/pH unit but within limited detection range from pH 7 to pH 9 in PBS. Measured pH sensitivity in PBS is higher than that from other reported CNT-based pH sensors. This high sensitivity is also observed in borate buffer solution (BBS).The effect of pH is to modify the threshold voltage of the FET, effect which is stronger on f-CNT FETs because of the functionalization. However, on f-CNT FETs, below pH 7, the threshold voltage becomes too close to the voltage limit (~ -1 V) for use of FETs in water, which explains the low sensitivity below pH 7.As-fabricated devices show a remarkable reversibility and lifetime of more than 10 months in water. However, the ambipolar behavior of f-CNT FETs is partially suppressed after 90 days and is totally degraded after 270 days in water; while the electrical characteristics of the p-CNT FET remains almost unchanged. This suggests a degradation of the polymer with time, whose mechanisms have not yet been studied.The response of the CNT-FETs to other analytes has also been tested in phosphate buffer solution. Both p-CNT FETs and f-CNT FETs similarly respond to Mg2+ in MgCl2 solution, whereas no significant response is observed in case of NaCl, KNO3 and HNO3.
• Halide ion migration and its role at the interfaces in perovskite solar cells
  
  • Kim Minjin
  • Jun Haeyeon
  • Lee Heejae
  • Nahdi Hindia
  • Tondelier Denis
  • Bonnassieux Yvan
  • Bourée Jean‐éric
  • Geffroy Bernard
  European Journal of Inorganic Chemistry, Wiley-VCH Verlag, 2021, 2021 (46), pp.4781-4789. Lead-halide perovskite solar cells (PSCs) based on unusual semiconductors made with ions, have shown impressive improvement in photovoltaic performance in few years exceeding nowadays 25 % power conversion efficiency. However, PSCs suffer from a lack of stability and show significant hysteresis in current-voltage curves, which are impeding commercialization. We confirmed the importance of halide ion migration in the hysteresis effect which has direct consequences on device efficiency. Using impedance spectroscopy, in addition to the geometrical capacitance found at high frequency for fresh samples without bias, we observed a second capacitance at low frequency after ageing or under bias. This second capacitance is interpreted as a charge accumulation layer at interfaces, which can be promoted by the presence of grain boundaries. Through glow-discharge optical emission spectroscopy elemental depth profiles, we found that under dark conditions, iodide ions diffuse through the electron transport layer versus ageing time. These ions interact chemically with the front-end electrode after four weeks and form silver iodide. (10.1002/ejic.202100654)
  DOI : 10.1002/ejic.202100654
• Area selective deposition of microcrystalline silicon by PECVD : physical origin, challenges and solutions.
  
  • Akiki Ghewa
  , 2021. This PhD thesis is devoted to the demonstration of a new area selective deposition process based on the plasma enhanced chemical vapor deposition (PECVD) technique and to understanding the physical origin behind it.The first section of the thesis exploits Ar/SiF4/H2 plasma chemistry to selectively and locally deposit microcrystalline silicon (µc-Si) thin films on silicon oxynitride (SiOxNy) while preventing its growth on aluminum oxide (AlOx). We found that this selectivity could be achieved for specific plasma conditions, which we term Area Selective-PECVD (AS-PECVD) conditions. Our plasma-based approach is a simple method that requires only one step to grow 55 nm of µc-Si selectively on SiOxNy for a relatively short time (20 minutes) compared to the alternative atomic layer deposition based approaches. The same AS-PECVD conditions provide selectivity on different materials as well, notably on metals. In this section, we also showed cases where the Ar/SiF4/H2 plasma deposition is not selective, and where silicon growth occurred on both SiOxNy and AlOx areas.In the second section, we focused on SiOxNy and AlOx surface chemistries in order to understand the reason behind our AS-PECVD process. X-ray spectroscopy based techniques were able to detect a great quantity of fluorine atoms on AlOx area due to the formation of Al-F bonds on top of this non growth area. Therefore, Ar/SiF4/H2 plasma under AS-PECVD conditions create a “chemical mask” of AlF3 preventing the nucleation of microcrystalline silicon on AlOx area.The last section included the application of the AS-PECVD process to patterned samples fabricated by photolithography. The preparation process causes surface contamination, so that additional cleaning and plasma pretreatment steps were necessary in order to obtain selective deposition. ASD is possible on smaller SiOxNy features (in the order of 15 µm). Although the morphology and the structure of the µc-Si slightly changed for different feature dimension, the growth rate did not. Since the selectivity can still be achieved on small areas, it remains possible that AS-PECVD can be used for semiconductor fabrication.
• Multi-scale modeling of water quality nanosensors based on carbon nanotubes and conjugated polymers
  
  • Benda Robert
  , 2021. We address in this PhD thesis water quality nanosensors based on polymer-functionalized carbon nanotubes networks. We derive a bottom-up multi-scale modeling strategy from the analysis of the possible sensing mechanisms of these chemical sensors. Several subscales arising from this bottom-up approach are treated quantatively. First, a functional form for the effective resistance of percolating network of carbon nanotubes, as a function of the main geometrical and physical parameters is derived by means of Monte-Carlo methods. To derive estimations of the resistance per unit length of a (functionalized) CNT from first principles, we decompose a (functionalized) nanotube interacting with several ions in water into different subsystems, which are studied indepently, choosing the appropriate model for each subscale (following a representativity--cost--accuracy compromise). A methodology is thus developed, based on existing electronic structure calculation methods and implicit solvent models, to study the interaction in water of an organic probe with a wide variety of closed-shell ions co-existing in water. We apply this general methodology to an example of probe developed in our team. Methodological developments and new algorithms in the context of the Restricted Open-Shell Hartree-Fock problem are presented, in view of treating more easily systems with open-shell ions. An alternative methodology, based on existing force field parametrization tools and molecular dynamics simulations codes, is established in order to derive another measure of the interaction strength of the ions--probe systems in explicit solvent, at the (classical or polarizable) force field level. Several existing methods for the computation of multipole moments, key parameters of polarizable force fields have been reformulated from a mathematical point of view and implemented in a new, more modular form (compatible with a larger number of quantum calculation codes). The interaction of a wide range of carbon nanotubes with conjugated polymers was also studied by means of molecular dynamics simulations, using an existing force field and one of its available parametrization, validated for this speficic use on benchmark model systems. Finally, we review the mechanisms governing the electronic transport occurring at room temperature in carbon nanotubes, and derive a possible methodology -- using the Boltzmann equation -- to include the leading mechanism (namely, the electron-phonon scattering) arising from this literature survey. We then apply this methodology to a simple model CNT--Cl- model system.
• Mueller matrix imaging for collagen scoring in mice model of pregnancy
  
  • Lee Hee Ryung
  • Saytashev Ilyas
  • Du Le Vinh Nguyen
  • Mahendroo Mala
  • Ramella-Roman Jessica
  • Novikova Tatiana
  Scientific Reports, Nature Publishing Group, 2021, 11 (1), pp.15621. Abstract Preterm birth risk is associated with early softening of the uterine cervix in pregnancy due to the accelerated remodeling of collagen extracellular matrix. Studies of mice model of pregnancy were performed with an imaging Mueller polarimeter at different time points of pregnancy to find polarimetric parameters for collagen scoring. Mueller matrix images of the unstained sections of mice uterine cervices were taken at day 6 and day 18 of 19-days gestation period and at different spatial locations through the cervices. The logarithmic decomposition of the recorded Mueller matrices mapped the depolarization, linear retardance, and azimuth of the optical axis of cervical tissue. These images highlighted both the inner structure of cervix and the arrangement of cervical collagen fibers confirmed by the second harmonic generation microscopy. The statistical analysis and two-Gaussians fit of the distributions of linear retardance and linear depolarization in the entire images of cervical tissue (without manual selection of the specific regions of interest) quantified the randomization of collagen fibers alignment with gestation time. At day 18 the remodeling of cervical extracellular matrix of collagen was measurable at the external cervical os that is available for the direct optical observations in vivo . It supports the assumption that imaging Mueller polarimetry holds promise for the fast and accurate collagen scoring in pregnancy and the assessment of the preterm birth risk. (10.1038/s41598-021-95020-8)
  DOI : 10.1038/s41598-021-95020-8
• Ageing mechanism of triple cation perovskite solar cells based on GD-OES
  
  • Kim Minjin
  • Dally Pia
  • Bouttemy Muriel
  • Tondelier Denis
  • Bourée Jean-Eric
  • Bonnassieux Yvan
  • Geffroy Bernard
  , 2021.
• Study of degradation mechanism in halide perovskite solar cells using impedance and modulus spectroscopy
  
  • Jun Haeyeon
  • Tondelier Denis
  • Geffroy Bernard
  • Bourée Jean-Eric
  • Swaraj Sufal
  • Bonnassieux Yvan
  , 2021. Organic inorganic hybrid halide perovskites have emerged as an innovative material with excellent optoelectronic properties, in bulk or as single crystals with low defect density with specific morphologies [1]–[3]. Perovskite solar cells (PSCs) have become a trending technology in photovoltaic research due to a rapid increase in efficiency in recent years. [4]. However, they show a degradation of their performance under operational conditions (light, bias, environmental stress, etc.). To increase their long-term stability is one of the biggest challenges for market applications. The presence of strong internal electric fields, the existence of ferroelectric domains, or the diffusion of ions/defects are suggested as possible causes for the degradation processes. Several authors suggest the existence of native vacancy defects in these materials and attribute to those defects a major role in the control of the optoelectronic properties, such as hysteresis in the photo-induced current-voltage curve, as well as in device degradation and lifetime. [5], [6] Among various degradation mechanism in PSCs, it’s important to understand the mechanism in both bulk perovskite and at the interfaces between perovskite layer and transport layers. Electrochemical impedance spectroscopy (EIS) is a powerful technique to examine the charge carrier dynamics in perovskite solar cells. It gives insight about internal electrical processes in PSCs and distinguishes between bulk and interfacial processes [7]–[9]. Each physical parameter can be extracted in the form of resistance (R), capacitance (C) and Warburg capacitance (W) using an equivalent electrical circuit model. In addition, dielectric modulus is applied for studying the microscopic mechanism of charge transport, contribution of grains (crystals) and grain boundaries and recombination dynamics [10]. In this study, we focus on the degradation of inverted planar structure perovskite solar cells through impedance and modulus spectroscopy. Two samples with the same structure are prepared and stored in air and under dark for 30 days. EIS is measured periodically, on the first sample, without J-V measurement to prevent EIS results from being affected by electrical field that occurs during J-V measurements, while J-V characteristic is measured periodically on the second sample. From combined impedance and modulus data, we confirmed that grains and grain boundaries can be distinguished. The results of modulus spectroscopy imply that the grain size decreases and grain boundaries increases which accelerates ionic accumulation and electronic polarization at interfaces. The results of J-V measurement confirms this hypothesis. Furthermore, we prepared two types of PSCs with electron transport layer based on wet- and dry- processes in order to investigate the effect of solvent on degradation mechanism.
• Bromine in triple mesoscopic hole-conductor-free perovskite solar cells
  
  • Nadhi Hindia
  • Cherif Sarah
  • Oswald Frédéric
  • Narbey Stéphanie
  • Plantevin Olivier
  • Geffroy Bernard
  • Tondelier Denis
  • Bonnassieux Yvan
  • Haddad Madjid
  , 2021. Within the challenging race for alternative energy sources, hybrid metal halide perovskite solar cells (PSCs) have undergone unprecedented progress with efficiencies reaching now 25.5% [1-3]. These remarkable performances result from the exceptional optoelectrical properties of hybrid perovskite materials. Coupled with their potential for low fabrication cost, perovskite solar cell technology is very promising. However, since hybrid halide perovskites have a highly ionic character, they can decompose under external stresses such as moisture, solvents and heating cycles [4-6]. Reducing environmental stresses imposed by moisture or oxygen for example, in order to improve the long-term stability of perovskite solar cells, is critical to the deployment of this technology. In 2017, Grancini et al [7] published a structure proven to be stable for more than 10,000 hrs, measured uned controlled standard conditions, by engineering an ultra-stable 2D/3D (HOOC(CH2)4NH3)2PbI4/CH3NH3PbI3 perovskite junction. This structure is based on a fully printable architecture made of three mesoporous layers in which the perovskite is embed. In this communication, we investigate the effects of changing the perovskite composition in this architecture by adding and/or replacing iodine with bromine into its chemical composition to tune device, increasing the band gap of the material [8], opening the gate to potential application in water splitting (VOC > 1.23 V at pH = 0 [9]). After characterization of their photovoltaic properties, the cells, reaching VOC ~1.3 V are studied by SEM coupled to EDX, XRD, Raman, absorption and photoluminescence spectroscopies. 1. Green, M. A., Ho-Baillie, A. & Snaith, H. J. The emergence of perovskite solar cells. Nature Photonics 8, 506–514 (2014). 2. Green, M. A. & Ho-Baillie, A. Perovskite Solar Cells: The Birth of a New Era in Photovoltaics. ACS Energy Lett. 2, 822–830 (2017). 3. Best Research Cell Efficiencies. NREL https://www.nrel.gov/pv/cell-efficiency.html (2021). 4. Berhe, T. A. et al. Organometal halide perovskite solar cells: degradation and stability. Energy Environ. Sci. 9, 323–356 (2016). 5. Leijtens, T. et al. Stability of Metal Halide Perovskite Solar Cells. Adv. Energy Mater. 5, 1500963 (2015). 6. Rong, Y., Liu, L., Mei, A., Li, X. & Han, H. Beyond Efficiency: the Challenge of Stability in Mesoscopic Perovskite Solar Cells. Adv. Energy Mater. 5, 1501066 (2015). 7. Grancini, G. et al. One-Year stable perovskite solar cells by 2D/3D interface engineering. Nature Communications 8, 15684 (2017). 8. Yu, W. et al. Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study. Chemical Physics Letters 699, 93–98 (2018). 9. Walter, M. G. et al. Solar Water Splitting Cells. Chem. Rev. 110, 6446–6473 (2010).
• Hydrogenated Silicon Nanoclusters with a Permanent Electric Dipole Moment for the Controlled Assembly of Silicon-Based Nanostructures
  
  • Jardali Fatme
  • Keary Bryan P
  • Perrotin Tatiana
  • Silva François
  • Vanel Jean-Charles
  • Bonnassieux Yvan
  • Mazouffre Stéphane
  • Ruth Albert A
  • Leulmi Mohamed E
  • Vach Holger
  ACS Applied Nano Materials, American Chemical Society, 2021, 4 (11), pp.12250-12260. While silicon nanoclusters have extensively been used for their outstanding properties for many decades, never before has their dipole moment been exploited for any application. Here, we have succeeded in producing hydrogenated silicon nanoclusters with a strong permanent electric dipole moment. This dipole moment allows us to use electric fields in order to orient and guide individual clusters. As a first example, we demonstrate the catalyst-free one-by-one self-assembly of one of the thinnest silicon nanowires yet observed. As a second example, we show that the simple presence of those nanoclusters on LaB 6 cathodes leads to a 30-fold enhancement of the thermionic electron current density over pristine LaB 6. Last but not least, the nanoclusters provide a protective layer against chemical and mechanical attack and largely prevent the evaporation of substrate materials, potentially increasing the operational lifetime of cathodes substantially. (10.1021/acsanm.1c02754)
  DOI : 10.1021/acsanm.1c02754
• Private know-how on "Synthesis of hybrid nanostructured anodes: Si Nanoparticles@Carbon nanotubes (SiNPs@CNTs) for Li-ion batteries
  
  • Cojocaru Costel Sorin
  • Ezzedine Mariam
  • Jardali Fatme
  • Florea Ileana
  , 2021.
• Comparative Study on the Quality of Microcrystalline and Epitaxial Silicon Films Produced by PECVD Using Identical SiF4 Based Process Conditions
  
  • Moreno Mario
  • Ponce Arturo
  • Galindo Arturo
  • Ortega Eduardo
  • Morales Alfredo
  • Flores Javier
  • Ambrosio Roberto
  • Torres Alfonso
  • Hernandez Luis
  • Vazquez-Leal Hector
  • Patriarche Gilles
  • Roca I Cabarrocas Pere
  Materials, MDPI, 2021, 14 (22), pp.6947. (10.3390/ma14226947)
  DOI : 10.3390/ma14226947
• Hydrogenated Silicon Nanoclusters with a Permanent Electric Dipole Moment for the Controlled Assembly of Silicon-Based Nanostructures
  
  • Jardali Fatme
  • Keary Bryan Patrick
  • Perrotin Tatiana
  • Silva François
  • Vanel Jean-Charles
  • Bonnassieux Yvan
  • Mazouffre Stéphane
  • Ruth Albert A
  • Leulmi Mohamed E
  • Vach Holger
  ACS Applied Nano Materials, American Chemical Society, 2021, 4 (11), pp.12250–12260. While silicon nanoclusters have extensively been used for their outstanding properties for many decades, never before their dipole moment has been exploited for any application. Here, we have succeeded in producing hydrogenated silicon nanoclusters with a strong permanent electric dipole moment. This dipole moment allows us to use electric fields in order to orient and guide individual clusters. As a first example, we 1 demonstrate the catalyst-free one-by-one self-assembly of one of the thinnest silicon nanowires yet observed. As a second example, we show that the simple presence of those nanoclusters on LaB 6 cathodes leads to a 30-fold enhancement of the thermionic electron current density over pristine LaB 6. Last but not least, the nanoclusters provide a protective layer against chemical and mechanical attack and largely prevent the evaporation of substrate materials potentially increasing the operational lifetime of cathodes substantially. (10.1021/acsanm.1c02754)
  DOI : 10.1021/acsanm.1c02754
• Development and characterization of Fired Passivating Contacts for p-type silicon solar cells fabrication
  
  • Desthieux Anatole
  , 2021. Due to its expected role in the energy transition, the photovoltaic industry is being challenged to reduce the environmental impact of the manufacturing of solar panels. The silicon solar cells with Tunnel Oxide Passivated Contact (TOPCon) technology are likely to broadly hit the market within the next years due to their great electrical performances. Yet their integration is rather energy intensive, which is why novel manufacturing options such as the Fired Passivating Contact (FPC) cells are being investigated.This dissertation presents the optimization of the deposition conditions of the various layers of a FPC cell, along with their thorough characterization. X-ray photoelectron spectroscopy analysis allowed to show that the deposition of a Plasma Enhanced Chemical Vapor Deposited (PECVD) (p) µc-Si:H layer modified the chemical composition of the buried tunnel oxide layer in the passivating stack.Improvements were made on an extit{in situ} Modulated Photoluminescence acquisition setup mounted on a PECVD reactor. This technique allows to monitor in real time the evolution of the passivation properties of a sample during a given processing step. In a case study, this resulted to the demonstration that the combined action of light and temperature on AlOx layers leads to the activation of stable positive fixed charges, which is highly unusual.The real-time lifetime measurements of FPC samples during a hydrogenation step evidenced the importance of the temperature and duration of the annealing step in order to fully achieve high passivation properties. The technique was also used during the SiNx:H deposition and allowed to show (i) the detrimental effect of direct H2 and NH3 plasma on FPC and especially on the ones based on (p) µc-SiOx layers, and (ii) that during the SiNx:H deposition, most of the improvement happens during the first minutes of deposition.The integration of FPC was carried out on large area mono-cast wafers with very promising results on polished surfaces.
• p-conjugated materials for electronic and optoelectronic applications
  
  • Yassar Abderrahim
  , 2021.
• A fiber-based endomicroscope designed for full Mueller endoscopic polarimetric imaging
  
  • Buckley Colman
  • Vizet Jérémy
  • Fabert Marc
  • Vanel Jean-Charles
  • Kinet Damien
  • de Martino Antonello
  • Pagnoux Dominique
  , 2021.
• Unraveling the physical information of depolarizers
  
  • van Eeckhout Albert
  • Gil Jose
  • Garcia-Caurel Enrique
  • Romero Javier García
  • Ossikovski Razvigor
  • José Ignacio San
  • Moreno Ignacio
  • Campos Juan
  • Lizana Angel
  Optics Express, Optical Society of America - OSA Publishing, 2021, 29 (23), pp.38811. The link between depolarization measures and physical nature and structure of material media inducing depolarization is nowadays an open question. This article shows how the joint use of two complementary sets of depolarizing metrics, namely the Indices of polarimetric purity and the Components of purity, are sufficient to completely describe the integral depolarizing properties of a sample. Based on a collection of illustrative and representative polarimetric configurations, a clear and meaningful physical interpretation of such metrics is provided, thus extending the current tools and comprehension for the study and analysis of the depolarizing properties of material media. This study could be of interest to those users dealing with depolarization or depolarizing samples. (10.1364/OE.438673)
  DOI : 10.1364/OE.438673
• In-situ Thermal Treatment of Octacyanometalate-Based Network into η-Carbides Nanoparticles
  
  • Blin Thomas
  • Florea Ileana
  • Fossard Frédéric
  • Girard Armelle
  • Mérot Jean-Sébastien
  • Catala Laure
  • Cojocaru Costel-Sorin
  • Huc Vincent
  • Loiseau Annick
  Microscopy and Microanalysis, Cambridge University Press, 2021, 27 (S2), pp.73-74. (10.1017/S1431927621013362)
  DOI : 10.1017/S1431927621013362
• In-situ ETEM Studies of Fe Catalyst NPs Formation under Molecular or Radicals/Activated Hydrogen Environments for the Growth of SWCNTs
  
  • Florea Ileana
  • Ezzedine Mariam
  • Zamfir Mihai-Robert
  • Truong Loan
  • Caristan Eleonor
  • Cojocaru Costel-Sorin
  Microscopy and Microanalysis, Cambridge University Press, 2021, 27 (S2), pp.85-86. (10.1017/S1431927621013428)
  DOI : 10.1017/S1431927621013428
• Plasma-Enhanced Chemical Vapor Deposition in a Transmission Electron Microscope?
  
  • Maurice Jean-Luc
  • Bulkin Pavel
  • Ngo Éric
  • Wang Weixi
  • I Cabarrocas Pere Roca
  • Foldyna Martin
  • Florea Ileana
  Microscopy and Microanalysis, Cambridge University Press, 2021, 27 (S2), pp.25-26. (10.1017/S143192762101312X)
  DOI : 10.1017/S143192762101312X
• Area Selective Plasma Enhanced Chemical Vapor Deposition of Silicon using a Fluorinated Precursor
  
  • Akiki Ghewa
  • Frégnaux Mathieu
  • Florea Ileana
  • Filonovich Sergej
  • Bulkin Pavel
  • Bouttemy Muriel
  • Johnson Erik V.
  , 2021.
• Analysis of Ion Migration and Ageing Characteristics for Triple-cation and CH3NH3PbI3-xClx Perovskite Based Thin-Film Solar Cells
  
  • Kim Minjin
  , 2021. FHybrid organic-inorganic perovskite materials (HOIPs) have emerged as an exciting research topic in chemistry and materials science for their attractive photoelectrical properties. The discovery of the potential of this material was considered by the journal Science as one of the ten most significant scientific breakthroughs in 2013. Lead-halide perovskite materials have been extensively studied for photovoltaic applications with power conversion efficiency nowadays over 25%. However, despite their processing advantages (low-cost solution process) and outstanding solar to electrical energy conversion properties, HOIPs materials suffer from several drawbacks such as environmental stability impeding their commercialization. It has been suggested that ionic migration in HOIPs could impact optoelectronic performance and affect device operation and long-term stability. However, despite considerable advancements in this research domain, several questions with respect to the physics of ions in perovskite materials remain unsolved. In this thesis, analyses of CH3NH3PbI3-xClx (MAPI) and Triple-cation Lead Halide {3CP: (MA0.17FA0.83)0.95Cs0.05Pb(I0.83Br0.17)3 (MA: Methylammonium, FA: Formamidinium)} based perovskite thin films and solar cells are presented.In a first step, the synthesis of the halide perovskite layer (3CP) is optimized by controlling the deposition conditions such as anti-solvent treatment, annealing condition, and dynamic- dispense process. 3CP based Perovskite Solar Cells (PSCs) are then manufactured in the inverted (p-i-n) planar structure and characterized optically and electrically in a second step.Direct experimental evidence of ion migration in HOIPs (MAPI and 3CP) under an applied constant electric field was found by the Glow Discharge Optical Emission Spectroscopy (GD-OES). In-situ and ex-situ GD-OES results showed that 3CP had faster ion migration recovery compared to MAPI. Through Impedance Spectroscopy (IS), the ion accumulation phenomenon at the interface was observed only with a voltage sweep for 2 min (range: -0.5 V ↔ +1.0 V). From IS measurement, a relative dielectric constant of 17 (MAPI) and 19 (3CP) is calculated for the perovskite materials.Finally, the ageing mechanism of the PSCs was investigated with solar cell performance ageing, IS, and GD-OES. An increase in ageing-related ion accumulation at the interface was observed for ten days. After long-term ageing, halogen ions were observed in the top silver electrode with GD-OES. The results demonstrate that halide ions in the HOIP layer diffuse into the top silver electrode in the form of silver halide (AgI and AgBr), as already mentioned in the literature.Researching ion migration and ageing characteristics proposes a perspective to understand why 3CP is more stable than MAPI. When developing a more improved perovskite material and evaluating the material properties, this study can suggest one criterion for material evaluation.
• Optimizing Mueller polarimetry in noisy systems through over-determination
  
  • Philpott Harry
  • Garcia-Caurel Enrique
  • Guaitella Olivier
  • Sobota Ana
  Applied optics, Optical Society of America, 2021, 60 (31), pp.9594. Mueller polarimetry measurements are increasingly being used to image highly dynamic and short-lived phenomena such as plasma discharges. For phenomena such as these, exposure times below 1 µs must be used. Unfortunately, these low exposure times significantly reduce the signal-to-noise ratio, making accurate and consistent measurements difficult. To overcome this limitation, we investigated increasing the number of Stokes vectors produced from a polarization state analyzer and polarization state generator, a process known as over-determination. To conduct our analysis, we used results from physical experiments using Stokes vectors generated by liquid crystal variable retarders. These results were then verified using data from simulations. First, we conclude that increasing the degree of over-determination is a simple and effective way of dealing with this noise; however, we also convey that choosing the best scheme is not an entirely trivial process. Second, we demonstrate that over-determination gives rise to hitherto inaccessible information that allows for the quantification of statistical noise and, crucially, the pinpointing of the origin of systematic error, a highly beneficial process that has been lacking until now. (10.1364/AO.435085)
  DOI : 10.1364/AO.435085
• Estimation of the Uncertainty due to Each Step of Simulating the Photovoltaic Conversion under Real Operating Conditions
  
  • Migan-Dubois Anne
  • Badosa Jordi
  • Bourdin Vincent
  • Torres Aguilar Moira
  • Bonnassieux Yvan
  International Journal of Photoenergy, Hindawi Publishing Corporation, 2021, 2021, pp.4228658. The simulation of photovoltaic installations is a major issue for their sizing, their smart grid operation, and their fault detection and diagnosis. In this article, we study in detail every step of the simulation chain, either from the global horizontal irradiance and the ambient temperature (i.e., 4 steps of simulation) or considering the global in-plane irradiance and the module operating temperature (i.e., 1 step of simulation). The average quality estimation of the models is made through the calculations of average annual error between estimations and measurements, from 2016 to 2020. We have shown that the most uncertain step is the conversion of the global irradiance in its diffuse and direct components (17.2%, 2 models tested). If the model goes up to the in-plane irradiance, the average annual error decreases to 5.3% (6 models tested). The photovoltaic module temperature calculation induces an error of less than 2°C (4 models tested with 2 configurations). Meanwhile, the photoelectrical conversion shows a 3.5% error, similar to the measurement uncertainties, considering as input, the modules temperature, and the in-plane irradiance. If the simulation goes from the global irradiance and the ambient temperature measured locally, the estimation leads to a 6.7% average annual error. If the local measurements are not available, we can use the closest meteorological station’s records (13 for our study), and the error becomes 12.1%. Finally, we can also use the satellite images that lead to a 15.2% error, for average per year. The impact of available input shows that modeling the DC photovoltaic production, using global horizontal irradiance and ambient temperature, gives rise to an error of 6.6% for local measurements, 12.1% for weather station measurements, and 15.2% for satellite images estimations. This article thus draws up a review of the existing models, allowing to calculate the DC production of a photovoltaic module, depending on the atmospheric conditions, and highlights the most precise or most critical steps, considering in situ and weather station ground-based measurements, and also estimation from satellite images. (10.1155/2021/4228658)
  DOI : 10.1155/2021/4228658
• Numerical and Experimental Studies of Pristine and Cluster containing Silane-Hydrogen Capacitively Coupled Plasmas Used for Silicon Epitaxial Growth
  
  • Zhang Tinghui
  , 2021. Based on the existed fluid model in our group , a 1D fluid model of radio-frequency (RF) capacitively-coupled silane/hydrogen plasmas that includes a detailed chemistry for silane-hydrogen discharge as well as the surface reactions to account for deposition and etching processes has been developed and tested against the experimental results. In particular, the surface chemistry including recombination, etching, and deposition reactions is coupled to the fluid model via a set of reaction probabilities. The 1-D fluid model was also coupled with a sectional model and transport equations to account for the formation of nanoparticles within plasma and the evolution of both size and charge distributions of the nanoparticles. To make the coupled 1-D fluid-sectional model computationally efficient, a time-splitting method was employed. Two groups of the fast and slow variables were defined depending on the characteristic time scale of their dynamics with respect to the period of RF field oscillations. The governing equations for two groups were solved in alteration by keeping the variables from another group as the “frozen” ones and using a smaller time step for the fast variable group compared to the time step for the slow variable group. The time averaged values of the fast variables (e.g. electrical potential, electron temperature, gas species densities, fluxes of species onto particles, nucleation rate, ion drag force) were used as the input values for the block of slow variable equations. The parametric tests were performed to find the optimal time-splitting conditions (fast and slow time steps, number of RF cycles for the fast variable block). The time-splitting approach was validated with the fully coupled code by using the same time step for both fast and slow variables. Also, the contribution of nanoparticles to the total deposition rate of silicon thin films was estimated and compared with experiments.Both numerical and experimental studies of the effects of gas pressure (1 to 3.5 Torr) and silane concentration (2 to 10%) on the deposition rate of silicon thin films in a standard plasma enhanced chemical vapor deposition (PECVD) reactor demonstrated that the deposition rate as determined from the optical modelling of UV-visible spectroscopic ellipsometry measurements agrees well with the modeling results. SiH3 radicals are found to be the main contributor to the computed deposition rates, whereas H3+ ions play the main role in the etching process.The developed 1-D fluid model can be used for the studies of complex silane/hydrogen plasma properties at different process conditions, thus, predicting the behavior of plasma species and nanoparticles at nanoscale that is not accessible with the direct in-situ measurement techniques.