Laser crystallization of silicon and study by finite element modelling

Laser crystallization of amorphous or microcrystalline silicon films to obtain high-quality polycrystalline films is one of the most promising methods for diminishing costs in the microelectronic and solar cells sectors. During a laser crystallization process light is partially absorbed by the amorphous silicon, heating the sample and, if the temperature rises high enough, causing the reorganization of the film structure into a crystalline one. In this work we show results on the crystallization of non-hydrogenated silicon thin-films by a continuous wave infrared laser, as well as a study of the process with a simple finite elements method (FEM) numerical model based in the dimensional non-linear heat transfer equation with a steady heat source

Finite element method modeling applied to laser crystallization of amorphous silicon

The crystallization by laser of amorphous or microcrystalline silicon films allows to obtain thin, high-quality, polycrystalline Si films, being a very promising method for diminishing costs in the microelectronic and solar cells sectors. During a laser crystallization process, light is partially absorbed in the amorphous silicon film, heating the sample and, if the temperature rises high enough, causing the reorganization of the film structure into a crys- talline one. In this work we show both experimental results on the crystallization of non-hydrogenated silicon thin-films performed by a continuous wave infrared laser are included, as well as a study of the process with a simple finite elements (FEM) numerical model based in the dimensional non-linear heat transfer equation with a steady heat source

Free form metallization of solar cells using Laser Induced Forward Transfer

Front metallization is an expensive, fundamental step in the fabrication of solar cells. Laser additive direct writing techniques, such as Laser Induced Forward Transfer (LIFT), can be used for printing optimized metallization patterns or free form personalized designs with applications in building integrated photovoltaics. In this work, metallic fingers and busbars have been printed onto different rigid and flexible photovoltaic materials using commercial, high viscosity, micron-sized particles, silver-based pastes. Printed lines show very large aspect ratios, low electrical resistivity and good adherence to the substrate. Functional test cells have been metallized from unfinished CIGS flexible solar cells

A comparative between IEEE and EN in the transformer derating when supplying nonsinusoidal load current. A practical case

Nowadays, power quality is a challenge for the distribution companies since the new energy policies are directed to a distributed generation system with power electronic based technologies. The reduction of distribution transformers capability when supplying nonsinusoidal load currents has a major impact within capacity reduction in distribution networks produced by technical losses. IEEE Std C57.110-2018, EN- 50464-3 and EN-50541-2 define procedures to derate transformers when supplying nonsinusoidal load currents. The aim of this paper is to compare these procedures through a real case distribution transformer that suffers problems due to high levels of current distortion.This research was funded by the “Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación” grant number “RTC-2017-6782-3”, the European Union FEDER funds with name “LOcalización de averías, monitorización de estado y Control en redes de bAja TEnsión—LOCATE” and the Horizon 2020 Program by the European Comision with project reference No 864579, H2020-LC-SC3-2019-ES-SCC

Just-In-Time eTraining Applied To Emergency Medical Services

While the applications of just-in-time training are more and more spread, the ubiquitous mobile technology has not found practical uses of this training strategy. As an original example of services for healthcare, we present in this work an application of eTraining that makes use of mobile telephones to transmit medical and on-site information content to emergency medical personnel that attend and emergency. The state-of-the-art in related technologies, overall architecture, and functioning of JITTER (for Just-In-Time Training for Emergency Responders) is described in this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This work has been funded by the FIT-350100-2006-400 PROFIT project of the Spanish Ministerio de Industria, Turismo y Comercio, American NSF grant DMI-0239180, NIEHS (National Institute for Environmental Health Sciences) grant 1R41ES014793-01, BanDeMar Networks, Inc., the healthcare company iSOFT Sanidad, S.A., and the CITIC Technology Centre

Laser functionalization of surfaces

The treatment of surfaces by physical or chemical methods is a very usual way to change their original properties. Although the most common use of a surface functionalization is for tribology aims, modifications of the topography that leads to changes in the surface roughness, its hydrophilicity or hydrophobicity, its light scattering behavior, biocompatibility or even aesthetic changes are possible. In this field, laser sources have proven to be a most versatile and useful tool, being a clean and fast way to achieve any of those objectives. In this work we show the results of functionalization by laser texturing of four different materials

LIFT front-contact metallization of silicon solar cells

© 2021 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Laser-Induced Forward Transfer (LIFT) is a very versatile technique, allowing the selective transfer of a wide range of materials with no contact and high accuracy. This work includes the analysis of heterojunction silicon solar cells with the frontal grid deposited by LIFT, and the electric characterization of the deposited lines.Partial financial support for this work has been provided by the Spanish Ministry of Science and Innovation under the projects CHENOC (ENE2016-78933-C4-1-R and ENE2016-78933-C4-4-R) and SCALED (PID2019-109215RBC41 and PID2019-109215RB-C44).Peer ReviewedPostprint (author's final draft

New strategies in laser processing of TCOs for light management improvement in thin-film silicon solar cells

Light confinement strategies play a crucial role in the performance of thin-film (TF) silicon solar cells. One way to reduce the optical losses is the texturing of the transparent conductive oxide (TCO) that acts as the front contact. Other losses arise from the mismatch between the incident light spectrum and the spectral properties of the absorbent material that imply that low energy photons (below the bandgap value) are not absorbed, and therefore can not generate photocurrent. Up-conversion techniques, in which two sub-bandgap photons are combined to give one photon with a better matching with the bandgap, were proposed to overcome this problem. In particular, this work studies two strategies to improve light management in thin film silicon solar cells using laser technology. The first one addresses the problem of TCO surface texturing using fully commercial fast and ultrafast solid state laser sources. Aluminum doped Zinc Oxide (AZO) samples were laser processed and the results were optically evaluated by measuring the haze factor of the treated samples. As a second strategy, laser annealing experiments of TCOs doped with rare earth ions are presented as a potential process to produce layers with up-conversion properties, opening the possibility of its potential use in high efficiency solar cells

Analysis by finite element calculations of light scattering in laser-textured AZO films for PV thin-film solar cells

In the thin-film photovoltaic industry, to achieve a high light scattering in one or more of the cell interfaces is one of the strategies that allow an enhancement of light absorption inside the cell and, therefore, a better device behavior and efficiency. Although chemical etching is the standard method to texture surfaces for that scattering improvement, laser light has shown as a new way for texturizing different materials, maintaining a good control of the final topography with a unique, clean, and quite precise process. In this work AZO films with different texture parameters are fabricated. The typical parameters used to characterize them, as the root mean square roughness or the haze factor, are discussed and, for deeper understanding of the scattering mechanisms, the light behavior in the films is simulated using a finite element method code. This method gives information about the light intensity in each point of the system, allowing the precise characterization of the scattering behavior near the film surface, and it can be used as well to calculate a simulated haze factor that can be compared with experimental measurements. A discussion of the validation of the numerical code, based in a comprehensive comparison with experimental data is included

Mobile just-in-time training application for emergency healthcare

While the applications of just-in-time training are more and more spread, the ubiquitous mobile technology has not found practical uses of this training strategy. As an original example of services for healthcare, we present in this work an application of eTraining that makes use of mobile telephones to transmit medical and on-site information content to emergency medical personnel that attend and emergency. The state-of-the-art in related technologies, overall architecture, and functioning of JITTER (for Just-In-Time Training for Emergency Responders) is described in this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech