Publications by Christophe Ballif

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Polysilicon recombination junctions whose n-type bottom layers double as a passivating contact to the silicon surface are investigated. Such recombination junctions are a key element in the interconnection of tandem devices with a silicon bottom cell, and ...

Silicon heterojunction solar cells critically depend on the detailed properties of their amorphous/crystalline silicon interfaces. We report here on the use of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy to gain precise ...

Perovskite-silicon (Si) tandem solar cells are the most prominent contenders to succeed single-junction Si cells that dominate the market today. Yet, to justify the added cost of inserting a perovskite cell on top of Si, these devices should first exhibit ...

Thin film silicon solar cells are attractive for photovoltaics; however, the poor charge transport in this material requires that the devices are thinner than the absorption length. Adequate absorption can nevertheless be achieved by light scattering at textured interfaces because light can get trapped inside the absorber layer if it is scattered into angles above the critical angle of total internal reflection. This situation can be identified with the propagation of a guided mode in a waveguide where sili

Tandem solar cells based on thin film silicon benefit from an intermediate reflector layer between the top and bottom cells since it enhances the absorption in the top cell. The top cell can thus be manufactured thinner and less prone to light induced degradation. Made from a thin layer of nanocrystalline silicon oxide, the interlayer provides a second functionality since it aids in the spatial separation of local shunts occurring in both sub-cells. Recently, the reflector morphology received attention sinc

AMPERE project, acronym for Automated photovoltaic cell and Module industrial Production to regain and secure European Renewable Energy market, is aimed to the setting-up of an innovative 200 MWp/y full-scale automated pilot line for the production of hete ...

We present tandem thin film silicon solar cells in n-i-p configuration with 12% initial efficiency. The stabilized efficiency of these devices is 10%. The result has become possible by the combination of a microcrystalline bottom cell with high current density and an asymmetric intermediate reflector that establishes a well adapted surface texture for the amorphous top cell. After successfully integrating these two steps, we obtain micromorph tandems cells with size of typically 0.25 cm2. The best cell amon

We introduce the concept of smoothening intermediate reflecting layers (IRLs) in Micromorph thin-film silicon tandem solar cells in the superstrate configuration. The aim of such structures is not only to provide a selective reflection of light for optimal ...

We investigate n-i-p/n-i-p micromorph tandem cells deposited at process temperature below 200°C in order to be compatible with low Tg (

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 ...

Several aspects of the science and technology of thin film silicon for photovoltaic applications will be presented. The potential advantages of this technology over crystalline wafer technology will be discussed. A basic understanding of the material properties of thin film silicon layers enables to assess their potential and limitations when used in photovoltaic devices. A brief review of the production technology for thin films will be given with particular emphasis on amorphous and microcrystalline silic

In the past few years, the importance of electric mobility has increased in response to growing concerns about climate change. However, limited cruising range and sparse charging infrastructure could restrain a massive deployment of electric vehicles (EVs) ...

We investigate the effect of light soaking and forward electric bias treatment on SHJ solar cells and modules, and in particular the influence of the thermal treatment occurring during lamination. A substantial performance increase is observed after electric bias or light soaking, which is shown to be potentially partly reset by the lamination process. This reset is reproduced by annealing the cells with the same thermal budget. A second treatment after lamination again improves performances, and a similar

In this contribution, the replication of nano-textures enhancing the short circuit current of thin film silicon solar cells onto low cost substrates (glass or PolyEthylene Naphtalate (PEN)) is studied. Optical and morphological analysis is performed to ass ...

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 ...

Single-junction microcrystalline silicon (mu c-Si:H) solar cells of selected i-layer crystalline volume fractions were light soaked (AM1.5, 1000 h at 50 degrees C) and subsequently annealed at increasing temperatures. The variations of subbandgap absorption during light soaking and during thermal annealing were monitored by Fourier transform photocurrent spectroscopy. The kinetics were shown to follow stretched exponential functions over long times such as 1000 h. The effective time constants appearing in t

Microchannel plates are vacuum-based electron multipliers for particle—in particular, photon— detection, with applications ranging from image intensifiers to single-photon detectors. Their key strengths are large signal amplification, large active area, mi ...

We evaluate the performance of thin-film silicon micromorph tandem solar cells deposited on transparent superstrates with embossed micrometer-scale 2-D gratings. Once coated with a thin conductive layer of hydrogenated indium oxide, the textured superstrates can be used as 2-D periodic single-texture front electrodes. Combining these almost loss-free front electrodes with a highly transparent, random self-textured zinc oxide layer (with a thickness 1 um) deposited by low-pressure chemical vapor deposition (

Implementing antireflection (AR) coatings in micromorph tandem solar cells is a challenging process in which not only more sunlight should get conducted into the cells, but also the current matching between subcells should either be maintained or get impro ...

The invention relates to a device comprising a conductive surface (12) and electrical contacts (14) by which an electric current is able to be passed. Said electrical contacts (14) comprise conductive seeds (16) deposited on the conductive surface (12), an ...

Christophe Ballif

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Passivating Polysilicon Recombination Junctions for Crystalline Silicon Solar Cells

Attenuated total reflectance Fourier-transform infrared spectroscopic investigation of silicon heterojunction solar cells

Synergetic substrate and additive engineering for over 30%-efficient perovskite-Si tandem solar cells

Excitation of guided-mode resonances in thin film silicon solar cells

Advanced intermediate reflector layers for thin film silicon tandem solar cells

AMPERE: a succesful project to regain European PV manufacture competitiveness

Micromorph n-i-p tandem cells with asymmetric intermediate reflectors

Smoothening intermediate reflecting layer for tandem thin-film silicon solar cells

ASYMMETRIC INTERMEDIATE REFLECTOR FOR N-I-P MULTI-JUNNCTION THIN FILM SILICON SOLAR CELLS

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

An Introduction To The Technology Of Thin Film Silicon Photovoltaics

Routing of Electric Vehicles With Intermediary Charging Stations: A Reinforcement Learning Approach

Transferability of the light-soaking benefits on silicon heterojunction cells to modules

NANO-IMPRINT TECHNIQUE FOR BACK REFLECTOR IN HIGH EFFICIENCY N-I-P THIN FILM SILICON SOLAR CELLS

Zinc blende-wurtzite polytypism in nanocrystalline ZnO films

Kinetics of creation and of thermal annealing of light-induced defects in microcrystalline silicon solar cells

Fabrication and characterization of monolithically integrated microchannel plates based on amorphous silicon

2-D Periodic and Random-on-Periodic Front Textures for Tandem Thin-Film Silicon Solar Cells

Simultaneous realization of light distribution and trapping in micromorph tandem solar cells using novel double-layered antireflection coatings

Device comprising electrical contacts and its production process