Publications by Christophe Ballif

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Silicon heterojunction solar cells have less manufacturing steps and have allowed achieving higher efficiency than PERC cells. However the market has been slow in taking up the technology. Here we discuss some of the obstacles that have been overcome in the last 10 years and show why the technology is now more ready than ever for a mass market launch. This bases on improvements at the device level reaching 24% with few process steps, on the availability of high-quality low cost n-type c-Si wafers, on improv

We describe a method based on nanoimprinting and non-absorbing insulating silicon nitride electrodes for evaluating the light trapping potential of photonic nanostructures for thin-film silicon solar cells. We validate our method by relating the optical reflectance of the full solar cell stack to the external quantum efficiency of functional cells. Our method provides a useful experimental tool to compare different nanostructures circumventing complications arising from parasitic absorption and electrical c

Single junction microcrystalline silicon solar cells presently reach confirmed efficiencies up to 10.1%. Further improvement on device quality is now necessary to continuously increase the electrical performances of the solar cells. Zones of porous materia ...

We demonstrate high-efficiency thin-film silicon solar cells with transparent nanotextured front electrodes fabricated via ultraviolet nanoimprint lithography on glass substrates. By replicating the morphology of state-of-the-art nanotextured zinc oxide front electrodes known for their exceptional light trapping properties, conversion efficiencies of up to 12.0% are achieved for micromorph tandem junction cells. Excellent light incoupling results in a remarkable summed short-circuit current density of 25.9

Vapor-based processes are particularly promising to deposit the perovskite thin film absorber of solar cells. These deposition methods are up-scalable, involve a controlled solvent-free environment, have the ability to conformally coat rough substrates, in ...

We investigate the structural evolution of polycrystalline zinc oxide films grown by low pressure metal-organic chemical vapor deposition. The goal is to achieve larger grains-leading to higher charge carrier mobility from lower grain boundary density-by c ...

Zinc and tin oxides are both earth-abundant materials with demonstrated applicability as electrodes in several optoelectronic devices. The presence of grain boundaries in these polycrystalline films generally limits the electron mobility. By a combinatoria ...

In this work the microstructure transition width from amorphous to microcrystalline silicon is discussed. It is shown that the width of the transition depends on the input silane concentration level and indirectly on the silane depletion level. The higher ...

Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with ...

This paper reports on the development of an innovative back-contacted crystalline silicon solar cell with passivating contacts featuring an interband tunnel junction at its electron-collecting contacts. In this novel architecture, named "tunnel-IBC", both ...

Angle resolved measurements of the external quantum efficiency of a-Si solar cells deposited on a grating show strong absorption phenomena which are well explained with the guided mode structure in an equivalent flat multilayer system.

Tandem solar cells that feature a high-bandgap perovskite cell on top of a lower bandgap silicon cell have the potential to reach efficiencies > 30%. Here, we present a versatile hybrid deposition method that yields conformal perovskite cells directly on t ...

Poly(ethylene-co-vinyl acetate) (EVA) is the primary polymer used for encapsulation of photovoltaic (PV) modules. Its degree of cross-linking (gel content) is taken as a major quality reference. The EVA gel content is normally measured by Soxhlet extractio ...

We discuss here optical losses in silicon heterojunction solar cells and strategies to minimize them. Optical losses originate from most non-crystalline-silicon layers involved in the solar cell. A breakdown for typical values is shown evidencing that supp ...

Excellent amorphous/crystalline silicon interface passivation is of extreme importance for high-efficiency silicon heterojunction solar cells. This can be obtained by inserting hydrogen-plasma treatments during deposition of the amorphous silicon passivati ...

We present an electrical model developed with LT SPICE that simulates the performance of a string of cells with disconnections in the electrical circuit. In a previous contribution, we quantified experimentally how the module performance is affected when o ...

A new approach is presented to determine the angular and spectral characteristics of light diffusely scattered from nanotextured front electrodes into the absorbing silicon layer of thin-film silicon solar cell devices.

• The identification and control of volatile organic compounds (VOCs) released by polymers during lamination in the photovoltaic (PV) industry is of considerable importance to establish and optimize processes in order to ensure a long term reliability of the manufactured modules. • Bubble formation is one of the cause of delamination, major problems linked to PV module reliability. • Gas chromatography-mass-spectrometry (GC-MS) is used to determine and quantify the VOCs emanating from EVA at 160 C and there

Thermal runaway is a major safety concern in the applications of Li-ion batteries, especially in the electric vehicle (EV) market. A key component to mitigate this risk is the separator membrane, a porous polymer film that prevents physical contact between ...

Christophe Ballif

Chat with Graph Search

The amazing improvement of silicon heterojunction technology: ready for a true mass market launch

Experimental Evaluation of the Light Trapping Potential of Optical Nanostructures for Thin-Film Silicon Solar Cells

MICROCRYSTALLINE SILICON SOLAR CELLS: EFFECT OF SUBSTRATE TEMPERATURE ON CRACKS

Nanoimprint Lithography for High-Efficiency Thin-Film Silicon Solar Cells

Vapor deposition of metal halide perovskite thin films: Process control strategies to shape layer properties

Increasing Polycrystalline Zinc Oxide Grain Size by Control of Film Preferential Orientation

High performance amorphous Zn-Sn-O: impact of composition, microstructure, and thermal treatments in the optoelectronic properties

Input silane concentration effect on the a-Si:H to uc-Si:H transition width

22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

Interdigitated back contact silicon heterojunction solar cells featuring an interband tunnel junction enabling simplified processing

Photocurrent Increase in Thin Film Solar Cells by Guided Mode Excitation

Hybrid sequential deposition process for fully textured perovskite/silicon tandem solar cells

Optical transmission as a fast and non-destructive tool for determination of ethylene-co-vinyl acetate curing state in photovoltaic modules

Paths for maximal light incoupling and excellent electrical performances in silicon heterojunction solar cells

Amorphous/crystalline silicon interface defects induced by hydrogen plasma treatments

Quantifying and Modeling the Impact of Interconnection Failures on the Electrical Performance of Crystalline Silicon Photovoltaic Modules

A New Approach to Light Scattering from Nanotextured Interfaces for Silicon Thin-Film Solar Cells

Insights on EVA lamination process: Where do the bubbles come from?

A New Approach to Light Scattering from Nanotextured Interfaces for Silicon Thin-Film Solar Cells

Ultrathin ALD Aluminum Oxide Thin Films Suppress the Thermal Shrinkage of Battery Separator Membranes