Publications

2025

• Rapport de conjoncture 2024 Section 08 Micro- et nanotechnologies, micro- et nanosystèmes, photonique, électronique, électromagnétisme, énergie électrique
  
  • Pera Marie-Cécile
  • Cueff Sébastien
  • Alonso Corinne
  • Bryche Jean-François
  • Castellon Jérôme
  • Charlot Benoit
  • Collin Stéphane
  • Destouches Nathalie
  • Dhillon Sukdheep
  • Dusch Yannick
  • Grenier Katia
  • Guéné Claire
  • Hoel Virginie
  • Martin Évelyne
  • Moncel Jean-Luc
  • Nikolayev Denys
  • Renaud Sylvie
  • Saint-Girons Guillaume
  • Salzenstein Patrice
  • Sarry Frédéric
  • van Dau Frédéric
  , 2025, pp.125-162. La Section 08 du CNRS rassemble 368 chercheurs, soit la 5e section la plus nombreuse. Ses thématiques couvrent l’ingénierie dans des domaines à fort impact sociétal comme l’énergie électrique, les communications et la santé. La période récente a été marquée par une plus forte prise en compte des enjeux environnementaux, l’essor des technologies quantiques, en particulier pour le calcul à basse consommation d’énergie et le recours aux outils de l’intelligence artificielle. Les réseaux électriques évoluent vers des modèles décentralisés et intelligents (smartgrids), intégrant des sources d’énergie renouvelable distribuées, ainsi que vers le développement de réseaux à haute tension continue. Cette transformation s’appuie sur la digitalisation, l’intelligence artificielle (IA) et l’utilisation de technologies innovantes comme en électronique de puissance, notamment avec les semi-conducteurs à grand gap et l’intégration verticale GaN. Les actionneurs électromécaniques visent à être plus performants, durables et intelligents, en s’appuyant sur des méthodes de conception par l’IA. Le stockage d’énergie joue un rôle clé, tant pour les réseaux que pour la mobilité, via les batteries et la voie hydrogène, les travaux consistent à optimiser les performances et la résilience de ces dispositifs tout en tenant compte de l’impact environnemental des solutions choisies. Les grandes tendances du domaine des ondes électromagnétiques et acoustiques se situent à plusieurs niveaux. La modélisation électromagnétique s’enrichit de l’hybridation des techniques usuelles et l’intégration d’intelligence artificielle pour les aspects multi-échelles, multiphysiques et milieux hétérogènes. Les développements technologiques et architecturaux dans la gamme des micro-ondes et millimétrique sont dominés par la montée en fréquence des systèmes de communication (5G et 6G) avec des largeurs de bandes passantes plus importantes et des niveaux de puissance plus élevés, tandis que le gap entre les THz et l’optique diminue. Reconfigurabilité, efficacité énergétique et intégration progressive des technologies par impression 3D et de matériaux biosourcés sont aussi en forte évolution tout en assurant une immunité électromagnétique des systèmes. Les effets sanitaires des nouveaux standards de communication sont également considérés avec des systèmes d’exposition appropriés et la prise en compte de l’exposome. Enfin les systèmes électromagnétiques et acoustiques d’analyse non destructives ou non invasives ciblent des résolutions d’imagerie toujours plus poussées. Les recherches dans le domaine de la photonique sont très actives et portent sur la conception de dispositifs pour l’émission de lumière (lasers, sources de photons uniques), le contrôle de la propagation (fibre optique) et de toutes les propriétés de la lumière, par exemple par la nanostructuration de matériaux (métasurfaces), par le contrôle du front d’onde dans des matériaux désordonnés, ou encore par l’utilisation d’effets non-linéaires. Nous décrivons en particulier trois domaines d’applications porteurs : l’imagerie pour le vivant, les horloges atomiques et les communications quantiques. En optoélectronique, les recherches visent à élargir les gammes spectrales des lasers et détecteurs (de l’UV au THz), avec une forte dynamique sur les VECSEL, les modulateurs ultrarapides pour les télécommunications et l’intégration des matériaux fonctionnels avec la photonique silicium. Le photovoltaïque poursuit des innovations sur les cellules tandem (pérovskites/silicium) pour augmenter l’efficacité tout en limitant l’impact environnemental. L’utilisation des matériaux 2D progresse dans l’optoélectronique avec des défis qui concernent principalement la stabilité des dispositifs, la croissance, et l’intégration à grande échelle. L’électronique évolue avec des approches de conception et des technologies plus sobres et plus durables. Les architectures neuromorphiques ou le calcul embarqué au plus proche du capteur limitent l’empreinte énergétique du traitement des données. L’évolution des technologies de packaging 3D pour les systèmes hétérogènes ou l’intégration des structures d’autotest améliorent la fiabilité des composants. Les solutions d’intégration 3D, au niveau des transistors ou des puces, sont toujours intensivement explorées. La co-intégration des composants, qu’elle soit optoélectronique pour les mélangeurs, ou bien CMOS/III-V pour les amplificateurs, est privilégiée pour le domaine des télécommunications THz/sub-THz. Dans le domaine des micro et nanosystèmes, ou microcapteurs MEMS, les travaux s’orientent vers les applications en environnement sévère et vers les micro sources d’énergie où le grappillage d’énergie servira à alimenter l’IoT. De plus, bon nombre de microsystèmes concernent l’environnement et les sciences de la vie par le développement de systèmes microphysiologiques comme les organes sur puces et les laboratoires sur puce. La nanofabrication à grande échelle a vu le développement de nouveaux procédés de nanostructuration comme la lithographie par nano impression, avec des résolutions comparables à celle de la lithographie électronique. Les enjeux principaux restent focalisés sur la minimisation de l’endommagement des surfaces et le contrôle dimensionnel à l’échelle nanométrique, notamment par des procédés avancés de gravure pas couche atomique, sur la gravure de métaux non conventionnels et la nécessité de diminuer l’empreinte carbone des procédés. Les technologies de transfert de couche et de collage se sont développées pour permettre l’intégration hétérogène de matériaux. Les travaux en bio-impression 4D permettent des avancées concernant les modèles in vitro (Organ on Chip), les médicaments de thérapie innovante, et les traitements personnalisés. Les propriétés d’auto-assemblage des brins d’ADN complémentaires (origamis d’ADN) sont utilisées pour construire des nano-objets ; l’introduction de nanoparticules permet d’obtenir des fonctionnalités optiques. L’intégration compacte de fonctions variées dans les composants suscite des recherches actives, visant à combiner entre eux des matériaux hétérogènes (III-V, oxydes, matériaux 2D, matériaux à changement de phase, pérovskites hybrides, matériaux organiques) à l’échelle nanométrique, sur plateforme silicium notamment. Ces recherches visent en particulier des applications en micro-optoélectronique, pour la récupération d’énergie ou le quantique. Les techniques de synthèse des matériaux s’adaptent à ces objectifs de co-intégration compacte, notamment par le développement de clusters permettant de combiner plusieurs techniques de dépôt dans le même process, ou de stratégies innovantes de contrôle en temps réel des procédés de croissance. Enfin, l’impact environnemental des matériaux et procédés est pris en compte de plus en plus systématiquement dans les stratégies de recherche (substitution des matériaux critiques, développement de procédés frugaux, etc.). De manière transversale, les travaux menés dans la section nécessitent le développement d’outils de simulation multi-échelle et multiphysique. Les outils de l’intelligence artificielle sont amenés à jouer un rôle clé afin d’accélérer la modélisation prédictive et l’optimisation des procédés et des dispositifs. La Section 08 est sensible à la promotion de la science ouverte et encourage la diffusion de bases de données, de logiciels en open source, qui est considérée comme un moyen de valorisation de l’activité de recherche.
• Organic Neuromorphic Circuits for Real‐Time Biosignal Applications
  
  • El-Nakouzi Sami
  • Kim Gibaek
  • Kim Yerin
  • Li Zonglong
  • Hemmati Amirmohammad
  • Golec Patryk
  • Zaibi Amer
  • Bonnassieux Yvan
  • Benwadih Mohammed
  • Iniguez Benjamin
  • Kadura Lina
  • Calvet Laurie E
  Advanced Electronic Materials, Wiley, 2025. <div><p>Organic neuromorphic circuits offer new opportunities for low-power, flexible electronics capable of real-time inference at the edge. In this work, we present a neuromorphic system based on organic thin-film transistors (OTFTs) that performs biosignal classification in a Bayesian framework. The spiking behavior of artificial OTFT neuron circuits are first characterized, showing how their dynamics can be tuned through circuit parameters. We then demonstrate how the circuits can infer information from real-world electroencephalography (EEG) data. When applied to epilepsy-related signal patterns, the system achieves excellent classification performance, while maintaining ultra-low power operation. These results highlight the potential of OTFT-based neuromorphic architectures for embedded medical diagnostics.</p></div> (10.1002/aelm.202500519)
  DOI : 10.1002/aelm.202500519
• Mitigation of Defect Formation at the NiO x /Perovskite Interface in p-i-n Perovskite Solar Cells
  
  • Hajhemati Javid
  • Mallik Nitin
  • Dufoulon Vincent
  • Frégnaux Mathieu
  • Regaldo Davide
  • Coutancier Damien
  • Schneider Nathanaelle
  • Tondelier Denis
  • Desta Derese
  • Boyen Hans-Gerd
  • Bonnassieux Yvan
  • Cacovich Stefania
  • Aureau Damien
  • Schulz Philip
  ACS Applied Materials & Interfaces, Washington, D.C. : American Chemical Society, 2025. (10.1021/acsami.5c18456)
  DOI : 10.1021/acsami.5c18456
• Low-Temperature, PECVD-Grown Nanocrystalline Silicon Oxide as a Metal Diffusion Barrier for Silicon Heterojunction Solar Cells
  
  • Patra Chandralina
  • Wang Junkang
  • Dembélé Kassiogé
  • Bulkin Pavel
  • Roca i Cabarrocas Pere
  • Johnson Erik
  ACS Applied Energy Materials, ACS, 2025. (10.1021/acsaem.5c02998)
  DOI : 10.1021/acsaem.5c02998
• Time Resolved Emission Spectroscopy of Si-doped MBE grown GaAsPBi
  
  • Jaffré Alexandre
  • Alamarguy David
  • Fukumoto Keiki
  • Ouaras Karim
  • Connolly James P.
  • Renard Charles
  • Mencaraglia Denis
  • Alvarez J
  • Kanjanachuchai Songphol
  • Himwas Chalermchai
  • Boutchich Mohamed
  , 2025. In this work, we study the electronic and luminescence properties of silicon (Si) doped MBE (molecular beam epitaxy) grown samples of GaAsPBi. Using Raman and photoluminescence techniques as well as Time- Resolved Emission Spectroscopy (TRES), at room temperature, we evidenced the emission mechanisms through deep-level traps by revealing hidden emission bands with different radiative recombination time constants. Band-to- band transitions have a ~220 ps radiative recombination lifetime regardless of the doping concentration level. In contrast, radiative recombination of the low energy part of the PL, expected to be related to band tail states significantly increase with the doping level from 600 to 3600 ps after pulsed-light excitation.
• Plasma-Driven Solid–Liquid Dynamics in Cu–Sn Catalysts and Nucleation of Silicon Nanowires Revealed by Environmental TEM
  
  • Wang Weixi
  • Ngo Eric
  • Bulkin Pavel
  • Foldyna Martin
  • Roca i Cabarrocas Pere
  • Johnson Erik V
  • Pribat Didier
  • Zhang Zhengyu
  • Maurice Jean-Luc
  Nano Letters, American Chemical Society, 2025, 25 (44), pp.15832-15839. We employ environmental TEM to observe phase transitions driven by plasma radicals, in Cu–Sn catalysts for silicon nanowire (SiNW) growth. Previously unrecognized solid–liquid dynamics enables the stable growth of ultrathin (∼7 nm) SiNWs with alternating cubic and hexagonal segments. At 250 °C, H radicals induce a solid–liquid Cu6Sn5–Sn nanostructure, defining small nucleation sites. At 400 °C, SiH3 radicals drive SiNW nucleation simultaneously with catalyst phase separation. A Sn-rich liquid supplies atomic steps that propagate into the solid catalyst. A solid Cu3Si phase remains epitaxially aligned with the SiNW, anchoring the liquid phase. The solid–liquid catalyst actively reorients, causing the Si step propagation direction to reverse periodically. These dynamic behaviors are reproduced using a Cu–In system, underscoring the versatility of combining high- and low-melting-point catalysts. Our findings demonstrate that plasma-radical-driven nonequilibrium chemistry can be harnessed to control nanowire growth at the atomic scale. (10.1021/acs.nanolett.5c03612)
  DOI : 10.1021/acs.nanolett.5c03612
• Accelerating Next-Gen Materials Discovery for Photovoltaic Applications Using AI-Driven Synthesis and Characterization
  
  • Chakar Joseph
  • Bonnassieux Yvan
  • Cacovich Stefania
  • Kleider Jean-Paul
  • Guillemoles Jean-François
  • Connolly James P
  • Puel Jean-Baptiste
  • Schulz Philip
  • Bonnassieux Yvan
  • Cacovich Stefania
  • Kleider Jean-Paul
  • Guillemoles Jean-François
  • P. Connolly James
  • Puel Jean-Baptiste
  • Schulz Philip
  , 2025. To 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.
• Carbon based electrode perovskite solar cells under real outdoor working conditions
  
  • Var Maximilien
  • Oswald Frédéric
  • Bonnassieux Yvan
  • Migan-Dubois Anne
  • Narbey Stéphanie
  • Jaffré Alexandre
  , 2025. The best-performing devices all use gold or silver as the back contact which limits perovskite solar cells large-scale application. However, the use of such noble metals is a source of instability in these devices. Performance and stability of triple mesoscopic perovskite solar cells with a carbon electrode, a promising architecture for the next generation of photovoltaics will be disclosed. Comparative study between indoor and outdoor tests is motivated by the lack of data on real conditions of use. In this work, we have tested the market readiness of new cell technologies by monitoring PSCs working under different operating modes (MPPT, MPPT+IV, on resistive load, open-circuit), outdoor and under controlled conditions. The operating point of these working mode is extracted from measured IV curves and compared to the real measured one, indoors and outdoors. Notable differences are observed. On resistive load, PSC performs better than expected, unlike MPPT cells.
• Fast-Tracking Solar Cell Materials Discovery Using Automation, Physics Modeling, and Bayesian Machine Learning
  
  • Chakar Joseph
  • Bonnassieux Yvan
  • Cacovich Stefania
  • P. Connolly James
  • Kleider Jean-Paul
  • Guillemoles Jean-François
  • Puel Jean-Baptiste
  • Schulz Philip
  , 2025. Combating climate change hinges on our ability to accelerate scientific breakthroughs, particularly in the development of future energy solutions. Luckily, artificial intelligence (AI) is making this possible by transforming every stage of materials development from conceptual design and synthesis to characterization and performance evaluation. In photovoltaics, AI is improving the reliability of mature technologies such as silicon and driving innovation in emerging solutions like perovskites, opening the door to higher efficiencies and broader deployment scenarios. In this work, we demonstrate how combining Bayesian machine learning with physics-based modeling not only accelerates scientific discovery but also improves the interpretability of black-box optimization in automated fabrication platforms. First, we showcase how our probabilistic Bayesian framework (Chakar et al., 2024, 10.1016/j.solener.2024.112595), combined with drift-diffusion modeling, offers a physically grounded alternative to conventional techniques by linking performance and stability metrics to interpretable parameters such as charge carrier mobility and defect densities. We highlight how this approach – which has been successfully validated for identifying photovoltaic degradation pathways, linking indoor and outdoor aging, and assessing passivation effects – can be extended to provide actionable feedback for automated platforms for the synthesis and characterization of novel perovskite solar cells. Specifically, we show how connecting batch-to-batch variability and performance improvements to fundamental cell properties helps pinpoint the automation steps that need further refinement. The ability to capture prediction uncertainty makes this approach particularly well-suited for multi-solution problems such as identifying performance bottlenecks and optimizing processes, where multiple routes can yield comparable outcomes. However, as this requires extensive simulations, Bayesian optimization (BO) emerges as a practical solution for navigating the search space more intelligently. Nonetheless, BO has its own set of challenges, particularly due to the curse of dimensionality and high computational cost when exploring large parameter spaces. We therefore introduce SCORE (Chakar, 2024, 10.48550/arXiv.2406.12661), a technique that can overcome these limitations and tackle key problems in solar energy research and beyond, providing a resource-efficient and accessible solution for a broad range of researchers. Finally, we describe how these tools will be integrated into a high-throughput platform being established at IPVF to support automated perovskite thin-film fabrication, characterization, and stability testing. Bringing together diverse research efforts, the platform will enable precise control over processing and measurement workflows, generating reproducible, high-quality data to accelerate joint research efforts across the perovskite community.
• Optical, electrochemical and charge transport properties of fully coplanar diketopyrrolopyrrole thiazole-based semiconductor material
  
  • Ren Shiwei
  • Wang Yujie
  • Huang Tingwei
  • Pan Liang
  • Chen Shuchang
  • Peng Hao
  • Chen Yijun
  • Zhao Yue
  • Zeng Wenxiang
  • Yassar Abderrahim
  • Wang Sichun
  • Chen Jinyang
  Journal of Materials Science, Springer Verlag, 2025. Pi-conjugated semiconductor material with multi-alkyl chains composed of thiazole, thiophene and diketopyrrolopyrrole moieties was designed and synthesized, named PDPP-2T-2Tz. Theoretical simulations confirmed that the molecular structure exhibits excellent coplanarity, which is essential for achieving efficient charge carrier transport. A series of photophysical and electrochemical tests were conducted to investigate its absorption characteristics and frontier orbital energy levels. Two-dimensional grazing-incidence wide-angle X-ray scattering (2D-GIWAXS) and atomic force microscopy (AFM) tests verified the high crystallinity and smooth film morphology of the material. The hole mobility of the annealed film-based transistor materials reached 0.33 cm 2 V -1 s -1 , demonstrating its potential applications in organic optoelectronics. (10.1007/s10853-025-11500-6)
  DOI : 10.1007/s10853-025-11500-6
• Influence of chemical and morphological properties on the mid-infrared refractive indices of Titan aerosol analogs
  
  • Perrin Zoé
  • Drant Thomas
  • Garcia-Caurel Enrique
  • Brubach Jean-Blaise
  • Ruscassier Nathalie
  • Gautier Thomas
  • Sciamma-O’brien Ella
  • Vettier Ludovic
  • Chatain Audrey
  • Guaitella Olivier
  • Carrasco Nathalie
  , 2025. In the atmosphere of Saturn's largest satellite, Titan, the solid particles in suspension (photochemistry organic aerosols) play an important role notably to the attenuation of the solar spectrum by absorption and scattering. To constrain these interactions, the optical properties of Titan’s atmospheric aerosols, refractive index n and extinction coefficient k were recovered from observations [1, 2, 3, 4]. The refractive indices database has been expanded using solid analogs of Titan's aerosols produced and analyzed in laboratory [5, 6, 7]. The experimental data are generally consistent with the optical properties derived from Titan’s aerosols, including the contribution to the extinction and albedo of Saturn's moon [5, 7, 8]. However, comparisons of vibrational modes in the mid-infrared (MIR) suggest a difference in composition between laboratory analogs and Titan’s aerosols [9, 10]. These discrepancies in the refractive indices of solids can originate from their morphological and chemical properties. Indeed, numerous experimental studies have revealed the variability in the morphology and chemical composition of solid analogs formed in simulations of Titan's atmospheric chemistry. (10.5194/epsc-dps2025-904)
  DOI : 10.5194/epsc-dps2025-904
• Refractive indices of Titan, Pluto and Exoplanet photochemical haze analogs from UV to far-IR : a comparative study between the PAMPRE and COSmIC experimental setups
  
  • Drant Thomas
  • Sciamma-O'Brien Ella
  • Jovanovic Lora
  • Perrin Zoé
  • Maratrat Louis
  • Vettier Ludovic
  • Garcia-Caurel Enrique
  • Wooden Diane
  • Rannou Pascal
  , 2025. The observations of planetary atmospheres and surfaces strongly rely on the use of experimental data to understand the interaction between light and particles. The intrinsic optical properties of these particles, also known as the refractive indices, describing light dispersion (i.e., n) and absorption (i.e., k), are required to consider the influence of their chemical composition. Only with these data can we interpret observations and avoid large degeneracy in the retrieval data analyses. Climate modeling is also strongly sensitive to these experimental data as atmospheric particles absorb and scatter radiations, and thus modify the temperature profile. Photochemical hazes are observed in the atmospheres of the different objects in the outer Solar System (Titan, Pluto, Triton, Jupiter, Saturn) as well as in exoplanet atmospheres (e.g., GJ1214 b). The observations of these different objects as well as the modeling suggest that the composition of photochemical hazes varies from one object to the next following changes in the irradiation efficiency, temperature, pressure and gas composition. These differences in composition suggest that the refractive indices of photochemical hazes are also function of pressure, temperature, irradiation efficiency and gas composition. In the present work, we produced laboratory analogs of these hazes from various gas mixtures with controlled abundances. We used 6 different gas compositions to mimic the atmospheric compositions of Titan, Pluto and exoplanets. Among the 6 conditions, we modified the N2/CH4 and CO/CH4 abundance ratios in the gas mixture to assess the influence of N2 and CO on the refractive indices of the haze material. In addition, we compared the influence of the experimental setup by using haze analogs produced with the PAMPRE (LATMOS, France) and COSmIC (NASA Ames, USA) experimental setups. This cross-laboratory comparison allows us to assess the influence of temperature, pressure, gas residence time and irradiation which are changing between PAMPRE and COSmIC. Using several optical measurements, we covered a broad spectral range from UV to far-IR (up to 200 microns) which is essential for climate calculations and to interpret the various remote-sensing observations of these planetary bodies. Our results revealed a significant difference between the refractive indices obtained on PAMPRE and COSmIC analogs, even for similar gas compositions. Based on previous elemental analyses of the haze analogs, we know that the COSmIC analogs are richer in nitrogen relative to carbon compared to the PAMPRE analogs. Here, we show that this difference in composition leads to higher n and k values for the COSmlC analogs in the entire spectral range. We found that changes in the CO/CH4 gas ratio have a rather poor influence on the refractive indices compared to the effect of the N2/CH4 ratio. We also found that hazes produced without nitrogen are more transparent in the entire spectral range from UV to IR with very different mid-IR absorption features that could help distinguish between N-rich and N-poor exoplanet atmospheres. These data should be used for future observational analyses and modeling simulations of sub-Neptune atmospheres and Solar System gas giants. (10.5194/epsc-dps2025-1740)
  DOI : 10.5194/epsc-dps2025-1740
• Adsorption analysis of Fe-ZQ on Cu(110) and V-ZQ on Au(110) using density functional theory
  
  • Denawi Adam Hassan
  • Hayn Roland
  Journal of Magnetism and Magnetic Materials, Elsevier, 2025, 628, pp.173203. (10.1016/j.jmmm.2025.173203)
  DOI : 10.1016/j.jmmm.2025.173203
• Adsorption analysis of Fe-ZQ on Cu(110) and V-ZQ on Au(110) using density functional theory
  
  • Denawi Adam Hassan
  • Hayn Roland
  Journal of Magnetism and Magnetic Materials, Elsevier, 2025, 628, pp.173203. This study investigates the behavior of polymers composed of transition metals (TM) and zwitterionic quinone (ZQ) molecules in two-dimensional (2D) configurations adsorbed on metallic substrates. We focus on the electronic and magnetic properties of these polymer chains, specifically those based on vanadium (V) and iron (Fe) atoms combined with zwitterionic quinone, when placed on Au(110) and Cu(110) surfaces, respectively. Our investigation employs SGGA + U calculations to provide detailed insights into the adsorption preferences and magnetic characteristics of these polymers. We find that V-ZQ polymers exhibit a preference for adsorption at the short-bridge site on the Au(110) surface. At this site, the vanadium atom displays a magnetic moment of approximately 3 mu B, indicating significant magnetic behavior. In contrast, Fe-ZQ polymers are most favorably adsorbed at the hollow (H) site on the Cu(110) surface, with a substantial adsorption energy Eads =-1.51 eV. The total magnetic moment per iron atom in these Fe-ZQ polymers is calculated to be 2 mu B, which corresponds to a spin state of S =1. An important charge transfer between substrate and monolayer is calculated, especially for the Cu substrate which influences, however, the local magnetic moments in a negligible way. Magnetic moments are stable despite a remarkable charge transfer. These findings highlight the distinct adsorption behaviors and magnetic properties of V-ZQ and Fe-ZQ polymers on different metallic surfaces, contributing to our understanding of their potential applications in nanotechnology and materials science. (10.1016/j.jmmm.2025.173203)
  DOI : 10.1016/j.jmmm.2025.173203
• A Highly Emissive Molecular Material with Tunable Emission Color: Investigations as Phosphor for the Elaboration of a Hybrid White-Light-Emitting Diode
  
  • Wang Shenming
  • Murga Cotrina Christian Julio
  • Roblin Jean-Philippe
  • Barros Anthony
  • Casaretto Nicolas
  • Denawi Adam Hassan
  • Vach Holger
  • Chadeyron Geneviève
  • Zucchi Gaël
  ACS Applied Optical Materials, ACS Publications, 2025, 3 (9), pp.2026-2038. 4,4′-([2,2′-Bipyrimidine]-5,5′-diyl)bis[N,N-bis(4-methoxyphenyl)aniline] (1), a molecular compound built by connecting an electron-deficient 2,2′-bipyrimidine core to two electron-rich triarylamine derivatives further enriched with electron-donating methoxy groups, was designed and synthesized for luminescent purpose. The X-ray crystal structure obtained from tetrahydrofuran (THF) and a dichloromethane (DCM)/hexane mixture revealed that 1 could adopt slightly different conformations in the solid state. Indeed, the bipyrimidine core is almost planar when the molecule is recrystallized from DCM/hexane and forms dimers, while a twist angle of 28.20°between the two pyrimidine rings and the formation of infinite π-stacks were found upon recrystallization from THF. Because of the donor-acceptor-donor structure and the resulting charge transfer, the molecule possesses some polarity in the excited state that makes it sensitive to its surroundings. As a consequence, solutions emitting from blue to red could be obtained by solubilizing 1 in solvents of various polarities. The presence of aromatic units is responsible for π-π-stacking interactions, as revealed by X-ray diffraction, leading to aggregation in solution and in the solid state, which also impacts the photophysical properties. A maximized phenomenon of aggregation-enhanced emission was observed in a THF solution containing 75% water. This sensitivity of 1 to the solvents in terms of photophysical properties was also demonstrated on films deposited from different solvents. These studies revealed the appropriate experimental conditions in which 1 can be highly emissive either in solution or in the solid state. Especially, a photoluminescence quantum yield as high as 82.2% was obtained in a film of 1 doped into poly(methyl methacrylate) at a rate of 10 wt %. Investigations on the photostability of 1 were performed under accelerated aging conditions (375 nm, 300 mW cm -2 ). Lowering the power resulted in an increase in stability and makes the molecular material an interesting candidate for luminescence purposes. (10.1021/acsaom.5c00228)
  DOI : 10.1021/acsaom.5c00228
• A Highly Emissive Molecular Material with Tunable Emission Color: Investigations as Phosphor for the Elaboration of a Hybrid White-Light-Emitting Diode
  
  • Wang Shenming
  • Murga Cotrina Christian Julio
  • Roblin Jean-Philippe
  • Barros Anthony
  • Casaretto Nicolas
  • Denawi Adam Hassan
  • Vach Holger
  • Chadeyron Geneviève
  • Zucchi Gaël
  ACS Applied Optical Materials, ACS Publications, 2025, 3 (9), pp.2026-2038. (10.1021/acsaom.5c00228)
  DOI : 10.1021/acsaom.5c00228
• A Universal Method for Achieving Ultra‐Low Contact Resistances in Organic Electrochemical Transistors
  
  • Lozano-Hernández Luis‐abraham
  • Rannou Patrice
  • Bonnassieux Yvan
  • Sanaur Sébastien
  Advanced Materials Interfaces, Wiley, 2025, 12 (16). Organic ElectroChemical Transistors (OECTs) are intensively studied for enabling their use in organic bioelectronics, neuromorphic systems, and biosensors. Beyond device geometry, reaching optimal operation of organic electronic circuits requires the optimization of the physico‐chemical properties of the channel. Toward this end, the effects of a “bulk” doping of the channel material and its influence on the contact resistance (R C ) at the interface between a Polymeric Mixed Ionic‐Electronic conductors (PMIECs) and the Source (S) and Drain (D) electrodes are presented. An easy‐to‐implement method to achieve ultra‐low contact resistances in OECTs is introduced. By incorporation of LiTFSI, a 4x transconductance improvement is achieved, and a decrease of R C by a factor of ≈2 and ≈40 has been observed for p‐ type or n‐ type PMIECs, respectively. It reaches an unprecedented width‐normalized contact resistance value as low as 1 Ohm.cm with the p(g2T‐T) polymer. The formation of very localized domains in the polymeric matrix in the vicinity of the electrodes, as a result of the reduction of TFSIˉ anions, which modulates the energy barrier at the S/D interface, is suggested here. Furthermore, both p(g2T‐T) and p(gNDI‐gT2) polymers exhibit low water uptake with minute amounts of LiTFSI. Worth noticing, doped p(g2T‐T) preserves its volumetric capacitance and demonstrates an exceptional long‐term stability. Finally, a universal strategy to fine‐tune OECT performances, drawing prospects for implementing next‐generation applications in organic bioelectronics and neuromorphics, is proposed. (10.1002/admi.202500208)
  DOI : 10.1002/admi.202500208
• Investigation of Patterned Plasma Etching Processes for HJT-IBC Solar Cells: Keys to Maintaining a High Electronic Quality Surface
  
  • Wang Junkang
  • Patra Chandralina
  • Wang Weixi
  • Ghosh Monalisa
  • Bulkin Pavel
  • Daineka Dmitri
  • Dembélé Kassiogé
  • Cabarrocas Pere Roca I
  • Ouaras Karim
  • Filonovich Sergej
  • Frégnaux Mathieu
  • Bouttemy Muriel
  • Johnson Erik
  Solar Energy Materials and Solar Cells, Elsevier, 2025, 288, pp.113653. (10.1016/j.solmat.2025.113653)
  DOI : 10.1016/j.solmat.2025.113653
• Investigation of Patterned Plasma Etching Processes for HJT-IBC Solar Cells: Keys to Maintaining a High Electronic Quality Surface
  
  • Wang Junkang
  • Patra Chandralina
  • Wang Weixi
  • Ghosh Monalisa
  • Bulkin Pavel
  • Daineka Dmitri
  • Dembélé Kassiogé
  • Cabarrocas Pere Roca I
  • Ouaras Karim
  • Filonovich Sergej
  • Frégnaux Mathieu
  • Bouttemy Muriel
  • Johnson Erik
  Solar Energy Materials and Solar Cells, Elsevier, 2025, 288, pp.113653. We 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 (i-a-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. (10.1016/j.solmat.2025.113653)
  DOI : 10.1016/j.solmat.2025.113653
• Investigation of Patterned Plasma Etching Processes for HJT-IBC Solar Cells: Keys to Maintaining a High Electronic Quality Surface
  
  • Wang Junkang
  • Patra Chandralina
  • Wang Weixi
  • Ghosh Monalisa
  • Bulkin Pavel
  • Daineka Dmitri
  • Dembélé Kassiogé
  • Cabarrocas Pere Roca I
  • Ouaras Karim
  • Filonovich Sergej
  • Frégnaux Mathieu
  • Bouttemy Muriel
  • Johnson Erik
  Solar Energy Materials and Solar Cells, Elsevier, 2025, 288, pp.113653. We 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 &gt; 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. (10.1016/j.solmat.2025.113653)
  DOI : 10.1016/j.solmat.2025.113653
• Hexagonal boron nitride thin film synthesis with a ns-pulsed MHCD: in-situ plasma diagnostics and post-growth film characterization
  
  • Menacer Belkacem
  • Stefas Dimitrios
  • Chazapis Nikolaos
  • Dembélé Kassiogé
  • Ouaras Karim
  • Lazzaroni Claudia
  • Gazeli Kristaq
  • Mille Vianney
  , 2025. Hexagonal boron nitride (h-BN) is deposited on Si &lt;100&gt; wafer (≈20 cm2) via Plasma Enhanced Chemical Vapor Deposition (PECVD) using a ns-pulsed N2/Ar Micro Hollow Cathode Discharge (MHCD) as a microplasma source. For the first time, aluminum nitride (AIN) is employed as the dielectric material in the MHCD to mitigate film contamination by atomic oxygen, an issue previously observed with conventional Al 2O3 dielectrics. A comprehensive multi-diagnostic approach is followed to characterize the deposited h-BN, including Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron microscopy (XPS). In parallel, in-situ diagnostics such as optical emission spectroscopy (OES) and intensified CCD (ICCD) imaging are used to monitor plasma properties, including emission profiles, gas temperature and discharge morphology. Raman spectra reveal the E2g phonon mode of h-BN around 1366 cm⁻¹, confirming successful synthesis. SEM imaging reveals an almost complete surface coverage by the film, with localized delamination. This is probably due to an uneven resistive heating of the Si wafer, rapid post-deposition cooling (∼13 K/min) and ambient exposure. AFM analysis indicates an average thickness of about 33 nm after 90 minutes of deposition (∼22 nm/h deposition rate). XPS measurements reveal an average B/N atomic ratio of ∼1.5 along the wafer diameter. Deviations from ideal film properties (e.g., stoichiometric unity, uniform morphology) are attributed to plasma-induced inhomogeneities (such as non-uniform species flux and temperature gradients) among other factors (e.g., ambient exposure post-deposition), which affect nitrogen and boron incorporation and localized film properties. Despite these challenges, the MHCD-driven PECVD process demonstrates strong potential for scalable h-BN synthesis, with further optimization of the reactor design, plasma conditions, and gas chemistry required to grow ideal films. (10.1063/5.0289220)
  DOI : 10.1063/5.0289220
• Deterioration of water evaporation by impurity accumulation at the liquid-vapor interface during nucleate boiling
  
  • Le Houedec Corentin
  • Tecchio Cassiano
  • Zajec Boštjan
  • Roca Pere
  • Bulkin Pavel
  • Nikolayev Vadim S
  , 2025. The interfacial resistance to evaporation, in particular for the case of water, is a longstanding issue. The previous data on its main characterizing parameter, the accommodation coefficient, manifest a dispersion over three orders of magnitude. We study the evaporation of a thin liquid layer (microlayer) under the growing single bubble in saturated pool boiling of ultra-pure water at atmospheric pressure. However, the water contamination during the experiment cannot be excluded. The local and instantaneous data on interfacial thermal resistance are recovered from the synchronous local measurements of the microlayer thickness and the heater temperature. At each particular interfacial point, the resistance shows a linear increase in time suggesting the effect of accumulation of impurities at the interface. We compute the water mass evaporated at a given point of microlayer that should be proportional to the interfacial concentration of accumulated impurities. A clear increase of the interfacial thermal resistance with the evaporated mass is observed. This demonstrates a link of the temporal increase of the interfacial resistance (i.e. the evaporation deterioration) with the accumulation of impurities at the interface, which can explain the dispersion of the published data on the accommodation coefficient.
• Perovskite solar cells with carbon-based electrodes monitored under different operating modes, in real outdoor and controlled conditions
  
  • Var Maximilien
  • Oswald F
  • Bonnassieux Yvan
  • Migan-Dubois Anne
  • Jaffré Alexandre
  • Parra J.
  • Narbey S
  , 2025. The best-performing devices all use gold or silver as the back contact which limits perovskite solar cells large-scale application. However, the use of such noble metals is a source of instability in these devices. Performance and stability of triple mesoscopic perovskite solar cells with a carbon electrode, a promising architecture for the next generation of photovoltaics will be disclosed. Comparative study between indoor and outdoor tests is motivated by the lack of data on real conditions of use. This communication describes the manufacture of the PSCs and the indoor (under constant illumination and regulated temperature) and outdoor (on the SIRTA observatory, with monitoring and measurements of environmental conditions) test platforms. The initial results, collected between July and November 2024, have shown differences in performance and lifetime according to the operating mode. (10.1038/ncomms15684)
  DOI : 10.1038/ncomms15684
• Compact classification using the biomimetic properties of ultrafast spiking microlaser neurons
  
  • Kim Gibaek
  • Dubernard Matthieu
  • El-Nakouzi Sami
  • Masominia Amir Hossein
  • Barbay Sylvain
  • Calvet Laurie E.
  Neuromorphic Computing and Engineering, IOPScience, 2025. Machine learning using spiking neurons offers high computational efficiency with minimal resources, enabling sparse coding and brain-inspired methods. Photonic systems potentially enable very fast classifications but, despite recent progress, demonstrations are still challenging to implement. While biomimetic properties of optically spiking neurons have been shown theoretically and experimentally, exploring how these characteristics can be used for a classification task has rarely been considered. Simulations of such architectures are hindered by the complexity of the numerical modeling necessary to accurately describe their properties. Here we show that a surrogate model based on a machine learning algorithm can accurately and efficiently describe a microlaser neuron’s biomimetic behavior for a specific targeted application. This enables the training of a compact, energy efficient spiking photonic architecture that takes advantage of biomimetic properties to detect important features of the data. The resulting classification accuracy is comparable to that of a multi-layer perceptron with higher structural complexity. We anticipate that our method is applicable to any spike-based excitable neuron hardware that exhibits similar biomimetic properties, enabling simulations of more complex biomimetic neuron architectures and ultimately more efficient hardware. (10.1088/2634-4386/ade1f4)
  DOI : 10.1088/2634-4386/ade1f4
• Exploring the Dynamics of Sn Droplets on Hydrogenated Amorphous Si and Ge Layers for Nanocrystal Design
  
  • Zhang Xiaoyang
  • Zhao Xuechun
  • Zheng Lulu
  • Florea Ileana
  • Cuvilly Fabien
  • Talbot Etienne
  • Roca I Cabarrocas Pere
  • Chen Wanghua
  Crystal Growth & Design, American Chemical Society, 2025, 25 (13), pp.4932-4939. Studying the interaction between metal droplets and amorphous layers can unlock the potential to nanocrystal design, enhance material properties, and provide fundamental knowledge. With the help of plasma-enhanced chemical vapor deposition (PECVD), this work explores the interplay between Sn metal droplets and amorphous layers (Si and Ge) by investigating two growth modes: standard mode (amorphous layer on metal droplets) and inverted mode (metal droplets on an amorphous layer). Based on these modes, in-plane NWs fabricated from a variety of amorphous layer stacks including single layers, bilayers, and up to 10 layers are compared and discussed. We found that nanostructures are obtained only when Sn droplets can interact directly with an amorphous Ge layer in the inverted mode. A wide variety of nanocrystals including NWs, nanobelts, and nanopillars are obtained when using an amorphous multilayer stack. The results are discussed based on surface tension and interfacial diffusion phenomena. (10.1021/acs.cgd.5c00423)
  DOI : 10.1021/acs.cgd.5c00423