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Refurbishment and remanufacturing play a vital role in the sustainability of the large industrial field, which aims at restoring the equipment that is close to the end of their life. The EU-funded project RECLAIM proposes new approaches and techniques to support these two activities in order to achieve saving valuable materials and resources by renewing and recycling the mechanical equipment rather than scraping them when they exceed the end of the lifetime. As the most critical part of predictive maintenance in RECLAIM, the fault diagnosis technique could provide the necessary information about the identification of the failure type, thus making suitable maintenance strategies. In this paper, we propose a novel implementation method that can combine the digital twins with the fault diagnosis of large industrial equipment. Experiment result and analysis demonstrate that the proposed framework performs well for the fault diagnosis of rolling bearing.

The highest efficiencies in single-junction solar cells are obtained with devices based on GaAs. As this material is reaching the limit in material quality, the optimization of the design of the cell becomes more important. In this study we implement a patterning technique to the bottom contact layer of thin-film GaAs solar cells that increases the reflectance of photons to the active layers. Both shallow junction and deep junction devices were evaluated, and for deep junction cells, both the short circuit current and the open circuit voltage increase with the reflectance. The radiative saturation current density also decreases, indicating increased photon recycling. Detailed model simulations are performed to further evaluate the mechanisms leading to the improved performance of the deep junction design. Based on the same model, the possibilities for further improvements utilizing the deep junction are also identified.

We report thin-film InAs/GaAs quantum dot (QD) solar cells with n − i − p + deep junction structure and planar back reflector fabricated by epitaxial lift-off (ELO) of full 3-in wafers. External quantum efficiency measurements demonstrate twofold enhancement of the QD photocurrent in the ELO QD cell compared to the wafer-based QD cell. In the GaAs wavelength range, the ELO QD cell perfectly preserves the current collection efficiency of the baseline single-junction ELO cell. We demonstrate by full-wave optical simulations that integrating a micro-patterned diffraction grating in the ELO cell rearside provides more than tenfold enhancement of the near-infrared light harvesting by QDs. Experimental results are thoroughly discussed with the help of physics-based simulations to single out the impact of QD dynamics and defects on the cell photovoltaic behavior. It is demonstrated that non radiative recombination in the QD stack is the bottleneck for the open circuit voltage ( V oc ) of the reported devices. More important, our theoretical calculations demonstrate that the V oc offset of 0.3 V from the QD ground state identified by Tanabe et al., 2012, from a collection of experimental data of high quality III-V QD solar cells is a reliable – albeit conservative – metric to gauge the attainable V oc and to quantify the scope for improvement by reducing non radiative recombination. Provided that material quality issues are solved, we demonstrate – by transport and rigorous electromagnetic simulations – that light-trapping enhanced thin-film cells with twenty InAs/GaAs QD layers reach efficiency higher than 28% under unconcentrated light, ambient temperature. If photon recycling can be fully exploited, 30% efficiency is deemed to be feasible.

The study presents a theoretical investigation of the impact of individual electron and hole dynamics on the photovoltaic characteristics of InAs/GaAs quantum dot solar cells. The analysis is carried out by exploiting a model which includes a detailed description of quantum dots (QD) kinetics within a drift-diffusion formalism. Steady-state and transient simulations show that hole thermal spreading across the closely spaced QD valence band states allows to extract the maximum achievable photocurrent from the QDs; on the other hand, slow hole dynamics turns QDs into efficient traps, impairing the short circuit current despite the extended light harvesting provided by the QDs.

This paper presents an experimental and theoretical study on the impact of doping and recombination mechanisms on quantum dot solar cells based on the InAs/GaAs system. Numerical simulations are built on a hybrid approach that includes the quantum features of the charge transfer processes between the nanostructured material and the bulk host material in a classical transport model of the macroscopic continuum. This allows gaining a detailed understanding of the several physical mechanisms affecting the photovoltaic conversion efficiency and provides a quantitatively accurate picture of real devices at a reasonable computational cost. Experimental results demonstrate that QD doping provides a remarkable increase of the solar cell open-circuit voltage, which is explained by the numerical simulations as the result of reduced recombination loss through quantum dots and defects.

[EN] The effects of the offset level and of the doping level in the perovskite layer upon both the reverse saturation current (J0) and the series resistance (Rs) of p-p-n perovskite solar cells have been researched in this paper, using five different materials such as spiro-OMeTAD, Cu2O, CuSCN, NiO and CuI, as Hole Transporting Material (HTM). The analysis was carried out by means of the single and double-diode models of a solar cell and of genetic algorithms based on optimization technique, in order to extract the desired parameters. The minor degradation of J0 and Rs has been found for the condition offset equal to zero and for the highest doping level in p-type perovskite layer. Also, a comparison has been made of the behavior of two reverse saturation currents (J01 and J02). The power conversion efficiency (PCE) has shown to be more strongly dependent on J02 than on J01. Results obtained in this work can be used to improve the manufacturing process of these devices., This work was partially supported by the National Council Research (CONICET), Argentina, by the Universidad Nacional Arturo Jauretche, Argentina, by the Universidad Nacional de Quilmes, Argentina, by the Universidad Nacional de La Plata, Argentina and by the Ministerio de Economía y Competitividad (Grant ENE2016-77798-C4-2-R), Spain

[EN] In this paper, a theoretical study of different p-p-n perovskite solar cells has been performed by means of computer simulation. Effects of the offset level upon the power conversion efficiency (PCE) of these devices have been researched using five different materials such as spiro-OMeTAD, Cu2O, CuSCN, NiO and CuI, as Hole Transporting Layer (HTL). The Solar Cells Capacitance Simulator (SCAPS)-1D has been the tool used for numerical simulation of these devices. A strong dependence of PCE has been found with the difference between the Maximum of the Valence Band of the HTL and perovskite materials, and with the doping level in p-type perovskite layer. A minimum value of hole mobility in the HTL has been also found, below which the PCE is reduced. Efficiencies in the order of 28% have been obtained for the Cu2O/Perovskite/TiO2 solar cell. Results obtained in this work show the potentiality of this promising technology., This work was partially supported by the Universidad Nacional de Quilmes, Argentina, by the Universidad Nacional Arturo Jauretche, Argentina, by the Universidad Nacional de La Plata, Argentina, by the National Council Research (CONICET), Argentina, and by the Ministerio de Economia y Competitividad (Grant ENE2016-77798-C4-2-R), Spain.

Fil: Cappelletti, Marcelo Angel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto de Investigaciones en Electronica, Control y Procesamiento de Senales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electronica, Control y Procesamiento de Senales; Argentina. Universidad Nacional Arturo Jauretche; Argentina

This paper presents a device-level model of quantum dot (QD) solar cells, coupling the classical drift-diffusion equations for transport of bulk carriers with a set of rate equations describing the QD carrier dynamics. The model is applied to carry out a detailed study of the impact of thermal-assisted processes on the electrical performance of InAs/GaAs QD solar cells (QDSCs), by exploiting experimentally determined parameters for QD photogeneration and carrier kinetics. Special emphasis is given on the analysis of the open circuit voltage degradation, as well as its dependence on QD size and carrier lifetime. The modeling approach is validated by comparing simulated trends against experimental data in the literature.

We report thin-film InAs/GaAs QD solar cells fabricated by epitaxial lift-off of 3-inch wafers containing QD epi-structures with high in-plane QD density. External quantum efficiency measurements demonstrate enhanced QD harvesting in the thin-film configuration. Numerical simulations show that remarkably high increase of the QD photocurrent may be achieved by replacing the planar rear mirror with micro-structured photonic gratings. Measurements of diffraction efficiency of grating prototypes realized on GaAs wafers by nanoimprint lithography are presented.

An iterative method based on numerical simulations was developed to enhance the proton radiation tolerance and the responsivity of Si PIN photodiodes. The method allows to calculate the optimal values of the intrinsic layer thickness and the incident light wavelength, in function of the light intensity and the maximum proton fluence to be supported by the device. These results minimize the effects of radiation on the total reverse current of the photodiode and maximize its response to light. The implementation of the method is useful in the design of devices whose operation point should not suffer variations due to radiation.

This paper presents a theoretical study of the effect of the nature of the carrier escape from quantum dots (QDs) on the performance of InAs/GaAs QD solar cells (QDSCs), based on numerical simulations. Excitonic and non-excitonic dynamics of electrons and holes are considered in the modeling, by assuming identical or separate time constants for the intersubband carrier transfer processes in the ground and excited states. It is shown that the excitonic capture and escape allow us to explain the non-additive characteristic of the QD photocurrent, observed when the total photocurrent of the cell is much lower than the sum of the photocurrents contributed separately by the barrier and the nanostructures. This behavior is practically eliminated in the non-excitonic case. The correlated dynamics under the non-excitonic scenario is analyzed by calculating the device sensitivity to small changes introduced in the escape time of electrons. It is stated that the non-variation of the QD photocurrent with this parameter could be interpreted as a consequence of either a correlated electron-hole escape from QDs, or a dominant recombination over the other involved processes. The ideality factor of the different QDSCs studied is also calculated from simulations under both concentrated sunlight and dark conditions. The obtained results are in line with experimental measurements published in the literature.

This paper presents a theoretical study about quantum dot solar cells by means of numerical simulations, considering different doping levels in the intrinsic region of the cells, with the aim of evaluating the effect on the device's power conversion efficiency. Results of simulations performed over GaAs solar cells with InAs quantum dots, based on two different fabrication processes, are reported. The donor doping density in the intrinsic region was ranged from 1013 to 1017 cm-3. It is shown that, for a doping level of 7×1015 cm-3, the contribution of larger sized quantum dots to the photocurrent is increased by 50%, a very promising result in the search for new designs with higher efficiencies. Fil: Cedola, Ariel Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ingeniería. Departamento de Electrotecnia. Grupo de Est.s/materiales y Disposit.electronicos; Argentina Fil: Gioannini, Mariangela. Politecnico di Torino; Italia Fil: Cappelluti, Federica. Politecnico di Torino; Italia Fil: Cappelletti, Marcelo Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ingeniería. Departamento de Electrotecnia. Grupo de Est.s/materiales y Disposit.electronicos; Argentina Fil: Peltzer y Blanca, Eitel Leopoldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ingeniería. Departamento de Electrotecnia. Grupo de Est.s/materiales y Disposit.electronicos; Argentina

En este trabajo se muestra el estudio realizado sobre materiales que serán utilizados en el diseño de una celda solar para su aplicación en el ciclo de producción de hidrógeno, también en este contexto se han estudiado compuestos capaces de almacenar el hidrógeno producido, de manera de cerrar el círculo propuesto de generación y almacenamiento de hidrógeno. En la primera etapa, se realizó el estudio de materiales semiconductores mediante primeros principios, con esta herramienta se estudiaron las propiedades electrónicas de los sistemas M:TiO2 (donde M: metales de transición 3d). En la segunda etapa, se llevó a cabo la modelización de una celda solar multijuntura, empleando los materiales obtenidos en la primera etapa. Mediante el diseño propuesto de la estructura de la celda solar se logró una eficiencia del 10% para la producción del hidrógeno. Finalmente, en la tercera y última etapa, una vez obtenido el hidrógeno, se realizaron estudios para determinar cuáles serían los materiales más viables para retener y liberar el H. Con esta finalidad, se estudiaron series de hidruros binarios y ternarios, con diferentes estructuras cristalinas, para determinar que compuesto presenta una mejor perspectiva para el almacenamiento de H., Facultad de Ingeniería

A theoretical study of the electrical performance of p-on-n GaAs sub-cells under AM0, irradiated with 1 MeV electrons, has been carried out by means of computer simulation. Effects of both base and emitter carrier concentration upon radiation resistance of these devices have been researched. From analysis it is possible to determine the highest electron fluence to which the electrical parameters of the solar cell, with well-known base and emitter carrier concentrations, are reduced simultaneously in less than 20% from their non-irradiated values. Results presented in this paper are important in order to contribute to the design of radiation-hardened devices.

The radiation resistance in InGaP/GaAs/Ge triple-junction solar cells is limited by that of the middle GaAs sub-cell. In this work, the electrical performance degradation of different GaAs sub-cells under 1 MeV electron irradiation at fluences below 4 × 1015 cm−2 has been analyzed by means of a computer simulation. The numerical simulations have been carried out using the onedimensional device modeling program PC1D. The effects of the base and emitter carrier concentrations of the p- and n-type GaAs structures on the maximum power point have been researched using a radiative recombination lifetime, a damage constant for the minority carrier lifetime and carrier removal rate models. An analytical model has been proposed, which is useful to either determine the maximum exposure time or select the appropriate device in order to ensure that the electrical parameters of different GaAs sub-cells will have a satisfactory response to radiation since they will be kept above 80% with respect to the non-irradiated values. Fil: Cappelletti, Marcelo Ángel. Universidad Nacional Arturo Jauretche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Departamento de Electrotecnia; Argentina Fil: Cedola, Ariel Pablo. Universidad Nacional de La Plata. Facultad de Ingeniería. Departamento de Electrotecnia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina Fil: Peltzer y Blanca, Eitel Leopoldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Departamento de Electrotecnia; Argentina

The performance of crystalline silicon n + / p / p + and n / n / p + solar cells under AM0 spectrum,irradiated with 1 MeV electrons at fluences below 10 17 cm −2 has been analyzed by means ofcomputer simulation. The software used, fully developed by the authors, solves numerically inone dimension under steady-state conditions, the Poisson and continuity equationsself-consistently. The influence of constructive characteristics and different levels of hazardousenvironmental work conditions on the maximum power point of over 150 devices has beeninvestigated. The study has allowed the authors to propose a useful analytical model related tothe constructive characteristics of the device such as polarity, base resistivity and totalthickness, with the aim of examining the electrical performance of Si space solar cells. Resultspresented in this paper are important in order to contribute to the design of radiation-hardeneddevices. 1. Introduction Taking into account the urgent need to make the most ofalternative energy sources, the study of semiconductor devicesthatcanprovidepoweratlowoperatingcost,suchassolarcells,is extremely important at the present time. Deep studies aboutso-calledthirdgenerationsolarcells,focusedonnewmaterialsand technologies such as intermediate band, quantum dots andhot-carrier devices [1–4], are being carried out with the aimof reducing the cost and increasing the efficiency with respectto the first generation, i.e. crystalline silicon (c-Si) solar cells.However, in present times a considerable amount of researchin the field of the photovoltaic cells is still dominated by theconventional c-Si devices.For space power applications, where the devices areexposed to irradiation of high energy particles, multijunction(MJ) solar cells based on III–V technologies havedemonstrated higher conversion efficiencies and radiation-resistance than c-Si devices [5–7]. Nevertheless, c-Si solarcells have proven to offer a worthy operational reliability andcosteffectivenessasaspacepowersource[8–10]andthereforefurther research in this topic is still required.Every different solar cell structure from a given material,total thickness, base resistivity and polarity (p- or n-type),is expected to respond differently as a function of radiation.Therefore, each device must undergo some kind of irradiationtest to determine the degradation characteristics. Nowadays,precise techniques of modeling and simulation have becomefundamental tools to predict and to improve the responseof electronic devices under different operation conditions,offering valuable knowledge at a much lower cost and in lesstime than experimentation.In order to contribute to the design of radiation-hardeneddevices, this paper presents a theoretical study of the behaviorof different c-Si n

In this paper, we present a study about Si and GaAs space solar cells by means of numerical simulations. We have investigated the variations of the short-circuit current, open circuit voltage and maximum power point, before and after the devices were irradiated with 10 MeV protons and fluences between 109 and 1013 p+ /cm2. The simulation results allow to obtain the optimum solar cell with specific requirements for space applications. Fil: Cappelletti, Marcelo Ángel. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Casas, Guillermo. Universidad Nacional de La Plata; Argentina. Universidad Nacional de Quilmes; Argentina Fil: Cedola, Ariel Pablo. Universidad Nacional de La Plata; Argentina Fil: Peltzer y Blanca, Eitel Leopoldo. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

An iterative method applied to enhance the proton radiation tolerance and the responsivity of PIN photodiodes was developed. The method allows to calculate optimal values of the intrinsic layer thickness and the incident light wavelength, in function of the light intensity and the maximum proton fluence to be supported by the device. These results minimize the effects of radiation on the total reverse current of the photodiode and maximize its response to light. The implementation of the method is useful in the design of devices that will not suffer variations from its operation point due to radiation.

In the present work, a complete numerical analysis of the influence of deep-trap levels on the dark current of silicon PIN photodiodes under 1 MeV neutron radiation was done. Results corroborate that energy levels near the mid-gap affect to a great extent the dark current. Radiation tolerances of undoped and gold-doped devices were compared through simulations. It has been concluded that gold in silicon reduces the neutron-induced damage. Finally, a model to calculate the dark current of irradiated devices doped with deep-impurities is presented.

This work focuses on study of radiation induced displacement damage effects on silicon PIN photodiodes at both, dark and illumination conditions, by mean of numerical simulations. For fluences greater than a certain limiting value, relation between photocurrent and dark current decreases below ten, leading to an undesirable device operation. An iterative method is proposed for design optimization of PIN photodiodes to be used under irradiation, that minimize radiation effects on total reverse current and maximize device response to incident light.

The experimental evolution of the threshold voltage of MOS devices during irradiation at changing bias voltages, exhibiting charging and neutralization of the oxide traps, was well fitted by a two-traps dynamic balance model. The values and field dependence of the extracted physical parameters are in close agreement with previously reported ones.

In the present work, the influence of deep-trap levels on the dark current of silicon PIN photodiodes under 1 MeV neutron radiation has been investigated by means of a complete numerical analysis. The computational code used for simulations, developed by the authors, numerically solves the coupled Poisson and continuity equations on a 2D domain to obtain the behavior of electronic devices. Recombination through deep levels in the bandgap is described by the Shockley–Read–Hall (SRH) theory. Defects caused by radiation are quantified in terms of the damage coefficient K for the minority carrier lifetime. The effects of the radiation studied are atomic displacement damages. Results corroborate that the dark current is strongly affected by energy levels close to the midgap. A relationship between the current damage rate and the trap level location in the silicon bandgap was obtained. A model to calculate the dark current of irradiated devices doped with deep impurities is presented. Simulations have allowed the comparison of radiation tolerances of undoped and gold-doped devices. The higher gold density has shown a marked improvement of the hardness of the devices to radiation effects.

A computer program for the simulation of semiconductor devices has been developed and applied to the analysis of radiation effects on Si PIN photodiodes. The study has allowed the authors to propose useful analytical models related to such optical and electrical device parameters as peak spectral response and dark current. Peak spectral response has shown a marked dependence on device layers dimensions. Dark current has demonstrated linear increase with intrinsic layer length and proton-radiation fluence. But the most important obtained result has been the determination of a particular set of semiconductor P-, I- and N-layer thicknesses, for given values of total device length and incident light intensity, that minimize radiation effects during photodiode operation in space environments up to high particle fluences.