Publications de Christophe Ballif

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NiOx is widely used as a hole transport material in perovskite solar cells (PSCs). This wide band gap p-type material is conveniently deposited via high throughput RF-sputtering, making it suitable for the industrialization of PSCs. Nonetheless, for the cells to pass accelerated degradation tests such as the IEC 61215 damp heat (DH) test, the chemistry of the NiOx film should remain constant at elevated temperaturs to preserve its optoelectronic properties. This study emphasizes that structural defects resu

Theory predicts that periodic photonic nanostructures should outperform their random counterparts in trapping light in solar cells. However, the current certified world-record conversion efficiency for amorphous silicon thin-film solar cells, which strongl ...

The deployment of distributed photovoltaics (PV) in low-voltage networks may cause technical issues such as voltage rises, line ampacity violations, and transformer overloading for distribution system operators (DSOs). These problems may induce grid reinfo ...

Residential photovoltaic systems often experience partial shading from chimneys, trees or other structures, which can induce hot-spots in the modules. If the temperature and frequency of these hot-spots are high, the module's reliability and safety may be ...

The Swiss energy transition, characterized by the nuclear phase-out, relies mainly on the integration of solar photovoltaic (PV), mostly because wind technology faces challenges in public acceptance. This study aims to analyse Swiss PV and wind generation data from 2020 to 2023 to assess their complementarity using statistical indicators and energy flow simulation. The results emphasize the time complementarity of both technologies through a strong correlation on monthly, daily and hourly intervals using Sp

This paper focuses on our latest progress in n-i-p thinmicromorph solar-cell fabrication using textured back reflectors and asymmetric intermediate reflectors, both deposited by lowpressure chemical vapor deposition of zinc oxide.We then present microcrystalline bottom cells with high crystallinity, which yield excellent long wavelength response for relatively thin absorber thickness. In a 1.5-μm-thick μc-Si:H single-junction n-i-p solar cell, we thus obtain a short-circuit current density of 25.9 mA·cm−2 ,

We report on the optoelectronic properties of ITO layers deposited by DC sputtering, using different oxygen to total flow ratios [r(O-2) = O-2/Ar, ranging from 1% to 8%], for silicon heterojunction (SHJ) solar cell application. The depth profiling of the v ...

A new in-situ moisture monitoring technique for photovoltaic (PV) modules is proposed using miniature digital humidity and temperature sensors. The sensors were embedded in three different ethylene-vinyl-acetate (EVA) stacks and proved to be resistant to l ...

The requirements for a micromorph tandem cell front transparent conductive oxide (TCO) are multiple. This essential layer needs a high transparency, excellent conduction, strong light scattering into silicon and good surface morphology for the subsequent growth of silicon cells. These parameters are all linked and trade-offs have to be found for optimal layer. The optimum combination, taking into account current achievable materials properties, is still unclear. Concerning transparency, we study here the im

In this article, the effect of the various processing steps during the fabrication of c-Si/SiOx/SiCx fired passivating contacts on the silicon bulk lifetime is studied, and the kinetics of defect deactivation by hydrogenation is investigated. It is found t ...

Maintaining electrical conductivity, optical transparency, and mechanical integrity against bending and stretching are key requirements for flexible transparent electrodes. Transparent conducting oxides (TCOs) are widely used thin film electrodes in optoel ...

We evaluate the effect of storage conditions of uncured encapsulant rolls and the potential consequences on photovoltaic (PV) module performance. We show the impact of residual water trapped inside laminated double glass PV modules after lamination and dur ...

High-efficiency amorphous silicon (a-Si:H) solar cells were deposited with different thicknesses of the p-type amorphous silicon carbide layer on substrates of varying roughness. We observed a light-induced open-circuit voltage (Voc) increase upon light so ...

We investigate the performance of hydrogenated indium oxide as a transparent front electrode for micromorph thin-film silicon solar cells on glass. Light trapping is achieved by replicating the morphology of state-of-the-art zinc oxide electrodes, known for their outstanding light trapping properties, via ultraviolet nanoimprint lithography. As a result of the high electron mobility and excellent near-infrared transparency of hydrogenated indium oxide, the short-circuit current density of the cells is impro

Solar cells based on organometallic halide perovskite absorber layers are emerging as a high-performance photovoltaic technology. Using highly sensitive photothermal deflection and photocurrent spectroscopy, we measure the absorption spectrum of CH3NH3PbI3 ...

High-efficiency crystalline silicon (c-Si) solar cells increasingly feature sophisticated electron and hole contacts aimed at minimizing electronic losses. At the rear of photovoltaic devices, such contacts-usually consisting of stacks of functional layers ...

We use a 1D grating back reflector to study the mechanism of light trapping in solar cells. Experimental results of a full solar cell on a sinusoidal back reflector are compared to a theoretical model using an expansion into grating modes and the Rayleigh hypothesis. By means of the sinusoidal shape, the continuity equations extend the coupling only to neighboring orders. The essential aspects of the coupling process are thus included, but the algorithm requires only a minimum amount of mathematical complex

Coupling of Earth-abundant hydrogen evolution catalysts to photoabsorbers is crucial for the production of hydrogen fuel using sunlight. In this work, we demonstrate the use of magnetron sputtering to deposit Mo2C as an efficient hydrogen evolution reactio ...

This work reports the electrical characterization of ZnSnxGe1-xN2 (ZTGN) layers deposited on glass by sputtering and further assesses for the first time the performance of SHJ solar cells featuring them as electron-selective contacts. Bandgap, conductivity ...

RE-BD AR2024, the 2024 Assessment Report on Renewable Energy and Biodiversity, addresses the critical balance between expanding renewable energy (RE) and better protecting biodiversity in Switzerland, with a special focus on the Alpine regions. It is the r ...

Christophe Ballif

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Stabilizing the Chemistry of NiOx in Perovskite Solar Cells to Pass the Damp Heat Test

Light trapping in solar cells: can periodic beat random?

Distributed flexibility as a cost-effective alternative to grid reinforcement

The effect of partial shading on the reliability of photovoltaic modules in the built-environment

Embracing Wind Power in the Solar Pv-Dominated Swiss Landscape

Optimization of the Asymmetric Intermediate Reflector Morphology for High Stabilized Efficiency Thin n-i-p Micromorph Solar Cells

Impact of the Oxygen Flow during the Magnetron Sputtering Deposition on the Indium Tin Oxide thin films for Silicon Heterojunction Solar Cell

In-Situ Monitoring of Moisture Ingress in PV Modules Using Digital Humidity Sensors

Transparent conducting oxide electrodes requirements for high efficiency micromorph solar cells

Bulk Defects and Hydrogenation Kinetics in Crystalline Silicon Solar Cells With Fired Passivating Contacts

Mechanical integrity of hybrid indium-free electrodes for flexible devices

The effect of storage conditions on the long-term stability of ethylene-vinyl-acetate (EVA) copolymer used in glass/glass modules

Light-induced Voc increase and decrease in high-efficiency amorphous silicon solar cells

Micromorph thin-film silicon solar cells with transparent high-mobility hydrogenated indium oxide front electrodes

Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance

Optical Evaluation of the Rear Contacts of Crystalline Silicon Solar Cells by Coupled Electromagnetic and Statistical Ray-Optics Modeling

Resonant absorption enhancement in solar cells with periodically textured interfaces

Solar Hydrogen Production by Amorphous Silicon Photocathodes Coated with a Magnetron Sputter Deposited Mo

ZnSnxGe1-xN2 as electron-selective contact for silicon heterojunction solar cells

RE-BD AR2024. Accelerating renewable energy development while enhancing biodiversity protection in Switzerland