Publications by Christophe Ballif

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We explore substoichiometric molybdenum trioxide (MoOx, x < 3) as a dopant-free, hole-selective contact for silicon solar cells. Using an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we demonstrate ...

We study n-i-p amorphous silicon solar cells with light-scattering nanoparticles in the back reflector. In one configuration, the particles are fully embedded in the zinc oxide buffer layer; In a second configuration, the particles are placed between the b ...

Thin film silicon is an attractive and versatile material for photovoltaics whose manufacturing reached a high level of maturity. Owing to its moderate efficiency compared to crystalline technologies, it should target either power plants with low installat ...

The electrification of minibus taxis in Africa is envisioned to play an important role in decarbonising transportation, reducing urban air pollution, and generating economic savings. However, comprehensive quantifications of these implications are scarce. This study introduces a modelling approach based on readily available data to simulate minibus operation and evaluate the key energy, environmental, and economic implications of such an electrification. Applying our model to nine diverse African cities, we

In this contribution, we shortly review the main features of amorphous/crystalline silicon heterojunction (SHJ) solar cells, including interface defects and requirements for high quality interfaces. We show how a process flow with a limited number of proce ...

We present advanced light trapping concepts for thin film silicon solar cells. When an amorphous and a microcrystalline absorber layers are combined into a micromorph tandem cell, light trapping becomes a challenge because it should combine the spectral re ...

Transition metal oxides (TMOs) are commonly used in a wide spectrum of device applications, thanks to their interesting electronic, photochromic, and electrochromic properties. Their environmental sensitivity, exploited for gas and chemical sensors, is how ...

Photovoltaics (PV) are promoted as an environmentally friendly alternative to carbon intensive energy sources, however, typical installations require expansive land-use. Building-integrated and building-applied photovoltaics (BIPV and BAPV) minimize this impact by use of pre-existing and non-productive surfaces for module installation. In these environments higher operating temperatures are expected because of reduced rear-side ventilation, which will have an impact on performance both instantaneously and i

The power conversion efficiency of most thin film solar cells is compromised by competing optical and electronic constraints, wherein a cell must be thick enough to collect light yet thin enough to efficiently extract current. Here, we introduce a nanoscale solar architecture inspired by a well-known radio technology concept, the coaxial cable, that naturally resolves this “thick–thin” conundrum. Optically thick and electronically thin amorphous silicon “nanocoax” cells are in the range of 8% efficiency, hi

Distributed rooftop photovoltaics (PV) is one of the pillars of the energy transition yet their widespread integration strains grids, leading to over-voltage, reverse power flow, and infrastructure strain. Furthermore, increased PV self-consumption reduces ...

Up-scalable coating processes need to be developed to manufacture efficient and stable perovskite-based solar modules. In this work, we combine two Lewis base additives (N,N′-dimethylpropyleneurea and thiourea) to fabricate high-quality Cs0.15FA0.85PbI3 pe ...

Hydrogenated amorphous silicon based microchannel plates (AMCPs) provide unique advantages over conventional glass-based microchannel plates, offering enhanced flexibility in manufacturing and vertical integration with an electronic readout. A high single-channel gain of 1500 could be measured in the latest generation, making them an attractive choice for a wide range of applications, including medical imaging, mass spectrometry, and particle physics experiments. A time resolution of 4.6±0.1ps (FWHM) was me

As global decarbonization accelerates the need for extensive solar photovoltaic deployment, land‐use conflicts have become increasingly pressing. Integrating PV into the built environment emerges as an effective strategy to mitigate these challenges by generating electricity where it is consumed. However, the polymeric encapsulant—a core material in photovoltaic (PV) modules—introduces critical fire safety concerns, particularly in building applications with strict regulatory requirements. This review addre

N-type nanocrystalline silicon (nc-Si:H(n)) layers are good candidates to improve current and transport properties in heterojunction solar cells. In this work, we perform thickness series alongside PH3 doping series to unravel the desirable characteristics ...

The rear side of a silicon solar cell is often designed to minimize surface recombination, series resistance, and cost, but not necessarily parasitic absorption. We present a comprehensive study of parasitic absorption in the metal layer of solar cells wit ...

Doped layers made of nanostructured silicon phases embedded in a silicon oxide matrix were implemented in thin film silicon solar cells. Their combination with optimized deposition processes for the silicon intrinsic layers is shown to allow for an increased resilience of the cell design to the substrate texture, with high electrical properties conserved on rough substrates. The presented optimizations thus permit turning the efficient light trapping provided by highly textured front electrodes into increas

ZnO bilayer films were deposited by low-pressure chemical vapor deposition in a single process step by controlling the differential doping of the nucleation and bulk parts of the layers. The resulting 2-μm-thick films are characterized by low free-carrier absorption and electron mobility over 40 cm2 /Vs. They, therefore, combine high transparency in the infrared region and moderate sheet resistance that can be lowered below 20 Ω/sq. These properties make ZnO bilayers ideal candidates as electrodes for the d

Radiation hard monolithic particle sensors can be fabricated by a vertical integration of amorphous silicon particle sensors on top of CMOS readout chip. Two types of such particle sensors are presented here using either thick diodes or microchannel plates. The first type based on amorphous silicon diodes exhibits high spatial resolution due to the short lateral carrier collection. Combination of an amorphous silicon thick diode with microstrip detector geometries permits to achieve micrometer spatial resol

Charge carrier collection in silicon heterojunction solar cells occurs via intrinsic/doped hydrogenated amorphous silicon layer stacks deposited on the crystalline silicon wafer surfaces. Usually, both the electron and hole collecting stacks are externally ...

We fabricated amorphous silicon n-i-p solar cells with two types of nanopatterned back reflectors using stencil lithography. One reflector type has a plasmonic grating that is embedded in the ZnO layer; the other one has a metallic grating patterned on top ...

Christophe Ballif

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Silicon heterojunction solar cell with passivated hole selective MoOx contact

Plasmonic silicon solar cells: impact of material quality and geometry

Light management in thin film silicon solar cells

Energy, environment, and economy implications of electrifying minibus taxis in African cities

A-Si:H/c-Si heterojunctions: a future mainstream technology for high-efficiency crystalline silicon solar cells ?

Light trapping effects in thin film silicon solar cells

Parasitic Absorption Reduction in Metal Oxide-Based Transparent Electrodes: Application in Perovskite Solar Cells

Outdoor Operating Temperature of Modules in BIPV and BAPV Topologies

Efficient nanocoax-based solar cells

Balancing DSO interests and PV system economics with alternative tariffs

Blade-Coating of High Crystallinity Cesium-Formamidinium Perovskite Formulations

Optimizing Photon Capture: Advancements in AMCP Technology for Enhanced Timing and Photon Detection Efficiency

Advanced Flame Retardant Strategies and Fire Performance Assessment for Safer Photovoltaics in Buildings: A Two‐Part Review

Integration of thin n-type nc-Si:H layers in the window-multilayer stack of heterojunction solar cells

Parasitic absorption in the rear reflector of a silicon solar cell: Simulation and measurement of the sub-bandgap reflectance for common dielectric/metal reflectors

Optimization of thin film silicon solar cells on highly textured substrates

New Generation Transparent LPCVD ZnO Electrodes for Enhanced Photocurrent in Micromorph Solar Cells and Modules

Amorphous silicon based particle detectors

Transparent Electrodes in Silicon Heterojunction Solar Cells: Influence on Contact Passivation

Stencil-nanopatterned back reflectors for thin-film amorphous silicon n-i-p solar cells