Publications by Christophe Ballif

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Commercial large-area solar simulators are principally in the form of Xenon flashers, which intrinsically have a short flash duration time, typically 100 ms at low spectrum quality and 10 ms at high spectrum quality. This implies measurement time constraints not adapted to the characterization of new generations of photovoltaic modules such as high-efficiency crystalline silicon modules, which can exhibit transient effects leading to measurement artifacts [1]. Moreover, thin film technologies require a high

We investigate lateral charge carrier transport in crystalline silicon solar cells. Under typical operation illumination of high-efficiency solar cells, a significant population of electrons and holes exist in the silicon wafer, leading to a non-negligible ...

The performance loss rate (PLR) is a key parameter in the assessment of photovoltaic (PV) systems' long-term performance and reliability. Despite the lack of industry-wide consensus and standardised methods for extracting PLR values from field data, the ye ...

Thin-film Si solar module production requires a fast wide area tool for layer characteristic measurement and control. Non-uniformity in layer deposition is expected to induce loss in module power. Simulations of amorphous Si modules using a two-dimensional model have been used to examine the efficiency loss associated with non uniformity of large scale monolithically integrated thin film modules. The results indicate that non uniform deposition significantly lowers the module efficiency, in a magnitude that

Recent improvements in light-emitting diode (LED) technology has allowed for the use of LEDs for solar simulators with excellent characteristics. In this paper, we present a solar simulator prototype fully based on LEDs. Our prototype has been designed spe ...

This work presents a systematic analysis of the transport mechanism and surface passivation of tunneling oxide (SiO2)/p-type poly-silicon (poly-Si(p)) junctions applied to p-type crystalline silicon (c-Si) solar cells by means of TCAD numerical simulations ...

Highly transparent electrodes with a well-tuned refractive index are essential for a wide range of optoelectronic devices, such as light emitting diodes and solar cells. Here, it is shown that the transparency of ZnO:Al can be improved and its refractive i ...

An approach that models the fabrication and enables the characterization of randomly self-textured silicon thin film solar cells is developed and are compared to experimental results. The optical and electrical properties of the solar cells depend on the m ...

Although charge‐carrier selectivity in conventional crystalline silicon (c‐Si) solar cells is usually realized by doping Si, the presence of dopants imposes inherent performance limitations due to parasitic absorption and carrier recombination. The develop ...

We determine the limiting efficiency for monolithic tandem solar cells that employ crystalline silicon for the top-cell as well as for the bottom cell. In such a design, the top-cell extends over the region of very high generation rate that forms at the fr ...

Electric vehicles (EVs) currently dominate the sales in the automotive market. A big leap in this market can be made by developing a photovoltaic product that can be integrated to an EV, as it can boost the driving range of the EV while reducing the chargi ...

High performance transparent conducting oxides (TCOs) have significance for optimising photovoltaic (PV) performance. The efficiency of the resulting solar cells is dependent particularly on achieving high light scattering, low resistivity and low absorpti ...

The drift length Ldrift=μτE within the i layer of a-Si:H solar cells is a crucial parameter for charge collection and efficiency. It is strongly reduced not only by light-induced reduction of μτ, but also by electric field deformation ΔE by charges near the p–i and i–n interfaces. Here, a simple model is presented to estimate contributions of free carriers, charges trapped in band tails and charged dangling bonds to ΔE. It is shown that the model reproduces correctly trends observed experimentally and by AS

Microchannel plates are electron multipliers widely used in applications such as particle detection, imaging, or mass spectrometry and are often paired with a photocathode to enable photon detection. Conventional microchannel plates, made of glass fibers, ...

We present a calculation routine for the angular and spectral dependence of scattered light after transmission through textured interfaces. Based on a modified Rayleigh–Sommerfeld integral, the treatment requires only measured surface profiles, and the refractive indices of the two materials adjacent to the textured interface but no fitting parameter. For typical surface morphologies used in solar cell fabrication, the calculations correctly reproduce the angle resolved scattering at 543 nm and the total sc

The thin-film limit is derived by a nonconventional approach and equations for transmittance, reflectance and absorptance are presented in highly versatile and accurate form. In the thin-film limit the optical properties do not depend on the absorption coe ...

Herein, challenges in the fabrication of full dopant-free bifacial silicon solar cells are discussed and efficient devices utilizing a MoO3/ indium tin oxide (ITO)/Ag hole-selective contact and ZnO/LiFx/Al electron-selective contacts with up to 79% short-c ...

An amorphous silicon solar cell on a periodic nanocone back reflector with a high 9.7% initial conversion efficiency is presented. The optimized back-reflector morphology provides powerful light trapping and enables excellent electrical cell performance. U ...

We investigate hole-selective passivating contacts that consist of an interfacial layer of silicon oxide (SiOx) and a layer of boron-doped SiCx(p). The fabrication process of these contacts involves an annealing step at temperatures above 750 degrees C whi ...

Damage of the hydrogenated amorphous/crystalline silicon interface passivation during transparent conductive oxide sputtering is reported. This occurs in the fabrication process of silicon heterojunction solar cells. We observe that this damage is at least partially caused by luminescence of the sputter plasma. Following low-temperature annealing, the electronic interface properties are recovered. However, the silicon-hydrogen configuration of the amorphous silicon film is permanently changed, as observed f

Christophe Ballif

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AN HYBRID LED/HALOGEN LARGE-AREA SOLAR SIMULATOR ALLOWING FOR VARIABLE SPECTRUM AND VARIABLE ILLUMINATION PULSE SHAPE

Lateral transport in silicon solar cells

Multi-Annual Year-on-Year: Minimising the Uncertainty in Photovoltaic System Performance Loss Rates

NEW PARADIGM FOR REAL-TIME MEASUREMENT AND MAPPING IN a-Si:H/uc-Si:H TANDEM DEVICES

Class AAA LED-Based Solar Simulator for Steady-State Measurements and Light Soaking

Numerical simulations of hole carrier selective contacts in p-type c-Si solar cells

Tuning the Optoelectronic Properties of ZnO:Al by Addition of Silica for Light Trapping in High-Efficiency Crystalline Si Solar Cells

From randomly self-textured substrates to highly efficient thin film solar cells: Influence of geometric interface engineering on light trapping, plasmonic losses and charge extraction

Mitigating Plasmonic Absorption Losses at Rear Electrodes in High‐Efficiency Silicon Solar Cells Using Dopant‐Free Contact Stacks

A recalculation of the efficiency limit in crystalline Si/Si tandem solar cells

Stress tolerance of lightweight glass-free PV modules for vehicle integration

The development of high performance SnO2:F as TCOs for thin film silicon solar cells

Charge collection in amorphous silicon solar cells: Cell analysis and simulation of high-efficiency pin devices

Optimizing photon capture: advancements in amorphous silicon-based microchannel plates

Modelling of light scattering from micro- and nanotextured surfaces

Thin-film limit formalism applied to surface defect absorption

Dopant-Free Bifacial Silicon Solar Cells

High-Efficiency Amorphous Silicon Solar Cell on a Periodic Nanocone Back Reflector

Nanoscale Study of the Hole-Selective Passivating Contacts with High Thermal Budget Using C-AFM Tomography

Damage at hydrogenated amorphous/crystalline silicon interfaces by indium tin oxide overlayer sputtering