Publications by Christophe Ballif

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We investigate the angular behavior of the upper bound of absorption provided by the guided modes in thin film solar cells. We show that the 4n2 limit can be potentially exceeded in a wide angular and wavelength range using two-dimensional periodic thin film structures. Two models are used to estimate the absorption enhancement; in the first one, we apply the periodicity condition along the thickness of the thin film structure but in the second one, we consider imperfect confinement of the wave to the devic

In amorphous/crystalline silicon heterojunction solar cells, an inversion layer is present at the front interface. By combining numerical simulations and experiments, we examine the contribution of the inversion layer to lateral transport and assess whethe ...

We report the recent advances and key requirements for high-efficiency "micromorph" tandem thin-film silicon solar cells composed of an amorphous silicon top cell and a microcrystalline silicon bottom cell. The impact of inserting a low-refractive-index si ...

Aluminum-doped zinc oxide (ZnO:Al) layers deposited by sputtering and boron-doped zinc oxide (ZnO:B) layers deposited by low-pressure chemical vapor deposition (LPCVD) are well-established materials for front electrodes in thin-film silicon solar cells. In ...

In this work, we investigate the relationship between potential-induced degradation (PID) and the bill of material used in module manufacturing. We manufacture samples with different combination of materials, using two types of solar cells (conventional vs ...

Finding the optimal structure to enhance light trapping in thin film silicon solar cells has attracted much attention in the previous decades. However, because of problems in integrating theory and experiment, there are only few comprehensive contributions that provide guidelines for the optimal design of such structures. In this work, a realistic thin film solar cell with almost conformal layers based on a one-dimensional metallic grating back-reflector is investigated through experiment and theory. The ex

Recently developed microchannel plates (MCPs) based on amorphous silicon offer potential advantages with respect to glass based ones. In this context, secondary electron emission (SEE) at very low energies below 100 eV has been studied for relevant materia ...

The electrification of road transport, as the predominant mode of transportation in Africa, represents a great opportunity to reduce greenhouse gas emissions and dependence on costly fuel imports. However, it introduces major challenges for local energy infrastructures, including the deployment of charging stations and the impact on fragile electricity grids. Existing planning tools often depend on detailed mobility data that is unavailable in many African contexts, especially for privately owned passenger

Microchannel plates fabricated from hydrogenated amorphous silicon (AMCPs) are a promising alternative to conventional glass microchannel plates. Their main advantages lie in their flexible fabrication processes, allowing for adaptable channel shapes and t ...

This contribution focuses on the fabrication and characterization of microchannel plates made of hydrogenated amorphous silicon (AMCPs). Flexible fabrication processes and the semi-conducting nature of amorphous silicon could give these detectors the advan ...

In this contribution, we study the increase in metalorganic-low pressure chemical vapor deposited (MO-LPCVD) ZnO thin films conductivity by hydrogen plasma post-treatment. We show that this improvement is linked to defect passivation at grain boundaries, decreasing the electron traps density and resulting in the almost complete suppression of the electron scattering at grain boundaries. For a 2 μm thick non-intentionally doped ZnO layer, electron mobility reaches after treatment values close to 60 cm2V-1s-1

Halide-perovskite semiconductors have a high potential for use in single-junction and tandem solar cells. Despite their unprecedented rise in power conversion efficiencies (PCEs) for photovoltaic (PV) applications, it remains unclear whether perovskite sol ...

The development of stable materials, processable on alarge area,is a prerequisite for perovskite industrialization. Beyond the perovskiteabsorber itself, this should also guide the development of all otherlayers in the solar cell. In this regard, the use o ...

We investigate the role of lateral transport of minority carriers in the wafer for front-junction solar cells. The study is based on two silicon heterojunction solar cells with p-type amorphous (a-Si), and nanocrystalline (nc-Si) silicon as hole selective ...

A high share of distributed photovoltaic (PV) generation in low-voltage networks may lead to over-voltage, and line/transformer overloading. To mitigate these issues, we investigate how advanced electricity tariffs could ensure safe grid operation while en ...

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characteriz ...

The wafers used by the photovoltaic industry are mostly produced by multi-wire slurry sawing. One of the key factors determining the wafer quality (presence of saw marks and chips, increased roughness, wafer thickness variations and wafer strength) is the ...

The remarkable recent progress in perovskite photovoltaics affords a novel opportunity to advance the power conversion efficiency of market-dominating crystalline silicon (c-Si) solar cells. A severe limiting factor in the development of perovskite/c-Si ta ...

Smart meters are a key component of the energy transition. The large amount of data collected in near real-time allows grid operators to observe and simulate network states. However, privacy-preserving rules forbid using such data for any applications other than network operation and billing. Smart meter measurements must be anonymised to transmit these sensitive data to a third party to perform network simulation and analysis. This work proposes two methods for data anonymisation that enable the use of raw

A new approach to reduce phosphorous contamination in the intrinsic layer during the deposition of amorphous silicon (a-Si:H) nip solar cells prepared in single-chamber reactors is presented. This novel process consists of a hydrogen etching plasma performed after the n-layer deposition, which prevents a recycling of phosphorous from the reactor walls when exposed to a hydrogen-rich plasma during the subsequent i-layer deposition. The implemented process reduces the phosphorous cross-contamination in the i-

Christophe Ballif

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Angular behavior of the absorption limit in thin film silicon solar cells

Analysis of lateral transport through the inversion layer in amorphous silicon/crystalline silicon heterojunction solar cells

High-Stable-Efficiency Tandem Thin-Film Silicon Solar Cell With Low-Refractive-Index Silicon-Oxide Interlayer

Comparison of LPCVD and sputter-etched ZnO layers applied as front electrodes in tandem thin-film silicon solar cells

One-type-fits-all-systems: Strategies for preventing potential-induced degradation in crystalline silicon solar photovoltaic modules

Enhanced light trapping in realistic thin film solar cells using one-dimensional gratings

A comprehensive analysis of electron emission from a-Si:H/Al2O3 at low energies

An open modeling framework to support the electrification of private transport in African cities: A case study of Addis Ababa

New Developments in Amorphous Silicon Based Microchannel Plates

Fabrication and Characterization of High Aspect Ratio Amorphous Silicon Based Microchannel Plates

Enhanced mobility of hydrogenated MO-LPCVD ZnO contacts for high performances thin film silicon solar cells

Linking Nanoscopic Insights to Millimetric-Devices in Formamidinium-Rich Perovskite Photovoltaics

Understanding and Mitigating the Degradation of Perovskite Solar Cells Based on a Nickel Oxide Hole Transport Material during Damp Heat Testing

Injection-dependent lateral resistance in front-junction solar cells with nc-Si:H and a-Si:H hole selective contact

Mitigating the impact of distributed PV in a low-voltage grid using electricity tariffs

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells

Effect of debris on the silicon wafering for solar cells

Light Management: A Key Concept in High-Efficiency Perovskite/Silicon Tandem Photovoltaics

Privacy Compliant Methods for Low-Volage Grid Simulations Using Smart Meter Data

Reduction of the phosphorous cross-contamination in nip solar cells prepared in a single-chamber PECVD reactor