Aïcha Hessler-Wyser

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The main drawback of Ni/YSZ anode supports for solid oxide fuel cell application is their low tolerance to reducing and oxidizing (RedOx) atmosphere changes, owing to the Ni/NiO volume variation. This work describes a structured approach based on design of ...

Improving the conductivity of earth-abundant transparent conductive oxides (TCOs) remains an important challenge that will facilitate the replacement of indium-based TCOs. Here, we show that a hydrogen (H-2)-plasma post-deposition treatment improves the co ...

ZnO is commonly observed and assumed to crystallize fully in a wurtzite structure. Indeed, While polytypism between a wurtzite and a zinc blende phase is often seen in some II-VI compounds, it has only rarely been observed in ZnO. Here, by means of automat ...

Carrier recombination at the metal contacts is a major obstacle in the development of high-performance crystalline silicon homojunction solar cells. To address this issue, we insert thin intrinsic hydrogenated amorphous silicon [a-Si: H(i)] passivating fil ...

Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500°C. The reduction is done under low hydrogen pressure. The reduction initiates at the NiO/YSZ interface, then moves to the center of the NiO grain. At higher temperature the reduction occurs also at the free NiO surface and the NiO/NiO grain boundaries. The growth of Ni is epitaxial on its oxide. Due to high volume decrease, na

Solid Oxide Fuel Cells (SOFC) common technology is based on anode- supported cells composed of nickel-yttria stabilized zirconia (Ni-YSZ) cermet. The nickel is in oxide state (NiO) during SOFC production and is reduced to metallic nickel during the first operation. The microstructure influences the SOFC electrochemical performance as well as its stability for long-term use. Oxidation of the nickel catalyst can occur at high fuel utilization and due to air leakage. The volume change from Ni to NiO can be det

This work aims to compare the effect of combined chromium and sulfur contaminating conditions to the Cr contamination alone on the Cr poisoning mechanisms in (La,Sr)MnO3-(Zr,Y)O-2 solid oxide fuel cell (SOFC) cathodes. Whereas Cr2O3 and (Cr,Mn)(3)O-4 are f ...

Replacing silver metallization with earth-abundant materials in Si solar cells is a critical step towards the sustainable growth of photovoltaics. In this work, we investigate fire-through processes using Al for the metallization of solar cells with p-type ...

The poor intrinsic perovskite absorber stability is arguably a central limitation challenging the prospect of commercialization for photovoltaic (PV) applications. Understanding the nanoscopic structural features that trigger instabilities in perovskite materials is essential to mitigate device degradation. Using nanostructure characterization techniques, we observe the local degradation to be initiated by material loss at stacking faults, forming inherently in the (011)-faceted perovskite domains in differ

Nanometer wide silicon filaments embedded in an amorphous silicon oxide matrix are grown at low temperatures over a large area. The optical and electrical properties of these mixed-phase nanomaterials can be tuned independently, allowing for advanced light management in high efficiency thin-film silicon solar cells and for band-gap tuning via quantum confinement in third-generation photovoltaics.

Nickel-Titanium (NiTi) shape memory alloys are often used in medical component devices, for instance as guide wires for neurological surgery applications. Manufacturing of such devices becomes more and more challenging, especially considering the need to j ...

As the performances of Solid Oxide Fuel Cells (SOFC) get attractive, long term degradation becomes the main issue for this technology. Therefore it is essential to localise the origin of degradation and to understand its processes in order to find solution ...

Environmental transmission electron microscopy is used in combination with density functional theory calculations to study the redox stability of a nickel/yttria-stabilized zirconia solid oxide fuel cell anode. The results reveal that the transfer of oxygen from NiO to yttria-stabilized zirconia triggers the reduction reaction. During Ni reoxidation, the creation of a porous structure, due to mass transport, accounts for the redox instability of the Ni-based anode. Both the expansion of NiO during a redox c

Whether illumination influences the ion conductivity in lead-halide perovskite solar cells containing iodide halides has been an ongoing debate. Experiments to elucidate the presence of a photoconductive effect require special devices or measurement techni ...

Microstructural evolution of anode supported solid oxide fuel cells (SOFC) during medium-term stack testing has been characterized by scanning electron microscopy (SEM). Low acceleration voltage SEM imaging is used to separate the three anode phases (nicke ...

This study aims to quantify in a holistic approach chromium (Cr) contamination in solid oxide fuel cell (SOFC) stack testing using adapted tools: i) a hot gas sampling method to analyze volatile Cr species in the air flux at the cathode inlet location; ii) a rapid quantification method for Cr as condensed matter in cathode material of post-test samples. The hot air sampling method reveals itself as a reproducible and time-resolved quantification technique for Cr trace amounts in a gas flow; this technique i

Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si sola ...

Crystalline silicon wafer (c-Si) can be extremely well passivated by plasma enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) films. As a result, on flat substrates, solar cells with very high open circuit voltage are readily obtained. O ...

Cell durability is a crucial technological issue for SOFC commercialization, and considerable progress has been made in recent years. A number of degradation pathways have been established, amongst which microstructural changes, poisoning effects and forma ...

Aïcha Hessler-Wyser

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Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part I: Microstructure optimization

Hydrogen plasma treatment for improved conductivity in amorphous aluminum doped zinc tin oxide thin films

Zinc blende-wurtzite polytypism in nanocrystalline ZnO films

Amorphous silicon passivated contacts for diffused junction silicon solar cells

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM

Combined Cr and S poisoning in solid oxide fuel cell cathodes

Interactions between aluminium and fired passivating contacts during fire-through metallization

Suppression of Stacking Faults for Stable Formamidinium-Rich Perovskite Absorbers

Silicon Filaments in Silicon Oxide for Next-Generation Photovoltaics

Characterisation of Laser Welds, between Nitinol and Stainless Steel Wires

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM

Quantitative study of anode microstructure related to SOFC stack degradation

In situ redox cycle of a nickel-YSZ fuel cell anode in an environmental transmission electron microscope

Assessing the Influence of Illumination on Ion Conductivity in Perovskite Solar Cells

Nickel-Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis

Multi-Scale Assessment of Cr Contamination Levels in SOFC Cathode Environment

Lithium Fluoride Based Electron Contacts for High Efficiency n-Type Crystalline Silicon Solar Cells

Modification of textured silicon wafer surface morphology for fabrication of heterojunction solar cell with open circuit voltage over 700mV

TEM investigation on zirconate formation and chromium poisoning in LSM/YSZ cathode