Fédération de Recherche PhotoVoltaïque

Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C.

Thermal treatment of the cell samples after dc sputtering of the Au electrodes enhanced the reproducibility of the perovskite cell efficiencies because the thermal annealing induced the strong adhesion between each layer of the cells.

Conjugation of low‐cost and high‐performance semiconductors is essential in solar‐driven photoelectrochemical (PEC) energy conversion. Sb 2 S 3 is a wide‐bandgap (≈1.7 eV) semiconductor with the potential to deliver a maximum photocurrent density of 24.5 mA cm −2 , making it highly attractive for PEC water splitting applications. However, bulk Sb 2 S 3 exhibits intrinsic recombination issues and low electron–hole separation, posing a limit to photocurrent generation. This study clarifies the carrier dynamics by ultrafast spectroscopy measurements and proposes the design of a heterojunction between Sb 2 S 3 and SnO 2 , with suitable band‐edge energy offset. The SnO 2 /Sb 2 S 3 heterojunction enhances the charge separation efficiency, resulting in improvement of the photocurrent. The SnO 2 /Sb 2 S 3 photoanode, fabricated entirely by vapor deposition processes, demonstrates photoelectrochemical water oxidation with a photocurrent density up to ≈3 mA cm −2 at 1.38 V versus RHE.

International audience

Tin oxide (SnOx) layers fabricated via atomic layer deposition (ALD) effectively serve as electron transport or sputter-resistant buffer layers in perovskite, silicon, and tandem solar cells, mitigating the interface defect density induced by transparent conductive oxide (TCO) in heterojunction (HIT) photovoltaic devices. This study introduces a 7 nm SnOx layer between P-doped amorphous Si (n-a-Si:H) and TCO to significantly enhance the minority carrier lifetime (MCLT). The incorporation of SnOx increased the MCLT of silicon wafers by approximately 32.5%, from 1328 to 1760 μs, measured at an excess carrier density of 1.0 × 1015 cm–3. UV–visible spectroscopy analysis determined the SnOx film bandgap to be 3.48 eV, facilitating effective absorption of plasma-induced radiation and substantially reducing damage during TCO deposition. X-ray photoelectron spectroscopy (XPS) reveals that SnOx (x ≈ 1.8) exhibits n-type conductivity, effectively passivating n-a-Si:H and mitigating plasma damage, enhancing MCLT. Consequently, the optimized photovoltaic device achieved superior performance, exhibiting a short-circuit current density (Jsc) of 40.84 mA/cm2, an open-circuit voltage (Voc) of 728 mV, a fill factor (FF) of 80.53%, and an overall power conversion efficiency (PCE) of 23.95%. These findings underscore the potential of ultrathin SnOx layers to enhance both efficiency and durability of advanced silicon-based solar cells.

The transition from descriptive regularities to prescriptive expectations is linked to the inherence heuristic (a cognitive shortcut attributing observed associations to inherent properties), reinforcing the perception of internal characteristics as defining features of social categories and contributing to gender stereotype endorsement. We investigated how inherent reasoning and moderating factors (i.e. generics and individual characteristics) influence the endorsement of gendered activities. Using a 3 (framing: generics vs. "most" vs. "some") × 2 (typicality: typical vs. countertypical gender associations) design, 241 French participants provided descriptive and prescriptive judgments about gendered associations, with justifications coded for inherence. Results showed that generic statements increased prescriptive judgments and reliance on inherent reasoning compared to “most” statements. Inherent justifications increased prescriptive judgments for typical and reduced them for countertypical gender associations. Inherent reasoning fully mediated the effect of generics on prescriptive judgments. These findings underscore the role of language and cognition in sustaining normative gender expectations.

This study presents a comprehensive mechanical and environmental stability assessment of sub-100 nm PECVD-grown silicon nitride (SiNx) antireflection coatings in single-layer (SLAR) and double-layer (DLAR) configurations for photovoltaic applications. Nanoindentation was performed on SiNx SLAR 75 nm with refractive index as 2.05 and SiNx DLAR as 55 nm/30 nm, R.I = 1.90/2.10 for top and bottom layer films following deposition temperature ranging from 300 to 400 °C. SiNx SLAR thin film exhibited excellent thermal resilience with hardness decreasing only slightly (15.845–15.666 GPa) and reduced modulus remaining stable (∼165 GPa), while SiNx DLAR coatings showed softening with an ∼2.3 GPa drop in hardness and ∼10 GPa in modulus, attributed to hydrogen effusion and matrix relaxation. Mean contact depths remained within 30% of the film thickness, validating the Oliver–Pharr modeling. AFM scans confirmed dense, defect-free surfaces with Rq 0.704 nm for SiNx SLAR and 0.355 nm for DLAR, establishing a high-quality baseline for durability tests. Under damp heat aging (85 °C/85% RH), minority carrier lifetime declined by 4.41% in SiNx SLAR and 2.65% DLAR, with subsequent H2-forming gas annealing enabling a partial recovery of 4.13% for SLAR and 2.59% for DLAR. These findings highlight the need to balance mechanical durability and thermal stability in designing reliable antireflection coatings for high-efficiency silicon solar cells.

The majority of evidence on the relations between young children’s levels of food neophobia (the fear of novel food), categorization abilities and executive functions is cross-sectional, leaving the direction of causality unclear. This study aimed to examine the bidirectional relations between children’s food neophobia, categorization performance and strategies, and executive functions (working memory, inhibition and cognitive flexibility) longitudinally. Children (n = 113; M age = 48.30 months at Time 1) were assessed at two time points over the course of a year of schooling. Controlling for age, early levels of food neophobia significantly predicted lower subsequent categorization performance and executive functions. No significant evidence was found to support the reverse directionality; neither categorization performance, strategies, nor executive functions at Time 1 predicted subsequent levels of food neophobia. The findings provide longitudinal evidence that neophobia hinders the development of categorization and executive functions abilities.

This chapter focuses on the parameter estimation of proton exchange membrane fuel cells (PEMFCs) in the context of transportation applications. With the increasing demand for clean and sustainable energy sources, PEMFCs have emerged as a promising technology due to their high efficiency, low operating temperature, and environmental friendliness. Accurate parameter estimation plays a crucial role in achieving reliable simulation and performance prediction of PEMFC systems. Various optimization-based methods have been employed to estimate the parameters of PEMFCs, considering the non-linear nature of the equations and characteristic curves involved. In this chapter, we explore the application of metaheuristic optimization algorithms. Besides, this chapter provides insights into the optimization-based techniques employed in the transportation sector to enhance the efficiency and reliability of PEMFCs, contributing to the development of sustainable power generation in transportation applications.

International audience

Re-using the substrate is identified as a method for reducing the cost of high efficiency III-V solar cells. The approach investigated here consists in inserting a graphene layer onto a (001)GaAs substrate prior to the epitaxial growth of GaAs. To obtain a monocrystalline GaAs grown layer, the graphene layer is patterned, followed by a two-step epitaxial growth, here performed by molecular beam epitaxy (MBE). The first step is a selective area growth of GaAs in graphene openings, followed by a lateral overgrowth, under a modulated Ga flux. The second step, after reaching coalescence, consists in a regular growth under continuous Ga supply. It is observed that the pattern orientations relative to the crystallographic direction of the GaAs substrate below the graphene have an influence on GaAs morphology and quality. The best result was obtained for patterns oriented along [1̅10]+22,5° with a graphene coverage of 50%, with a significantly reduced roughness down to 3,3nm.

An innovative two-terminal III–V/c-Si multijunction device is constructed using direct electrode connections and extending the bottom area to improve carrier transport and current matching between the top III–V and bottom c-Si devices. A commercial triple junction GaInP2/InGaAs/Ge top cell (1 cm2) with a complete cover electrode at the rear is connected directly to a silicon heterojunction (SHJ) bottom device using silver paste. The area of the SHJ bottom device is enlarged from 0.69 cm2 to 15 cm2 to match the current density of the top. With a small active area of 0.69 cm2, the bottom device has a current density of 13.6 mA/cm2, comparable to the top device’s (13.5 mA/cm2). By optimizing the SHJ bottom, the multijunction device achieves an impressive efficiency of 39.5% with a short circuit current density of 13.5 mA/cm2, an open circuit voltage of 3.45 V, and an 85% fill factor. This initial design demonstrates the potential to significantly improve the efficiency of a two-terminal III–V/c-Si tandem device by increasing the matching current levels of both top and bottom cells.

Disgust reactions significantly impact food choices, particularly in meat consumption, yet the factors influencing their intensity and how individuals justify them remain underexplored. This study (n = 217) provides a novel, comprehensive examination of both disgust intensity and justification patterns across seven meat categories: cultured meat, genetically modified meat, game meat, small farm meat, factory-farmed meat, endangered animal meat, and pet meat. Results revealed that disgust sensitivity and gender significantly impact responses, with women reporting higher disgust intensity and greater likelihood to cite moral concerns as justification. Importantly, our study reveals a previously unidentified interaction effect: familiarity moderates the relationship between perceived naturalness and disgust intensity, suggesting a strategy to enhance acceptance of sustainable food alternatives. The justification patterns exhibited systematic variation by meat type. By bridging core and moral disgust research traditions, this work advances our understanding of how disgust functions at the intersection of biological protection and moral judgment.