Optimisation des paramètres de dépôt de a-Si:H dans la technique Hg-photo-CVDK

Optimizing deposition parameters of a-Si:H in Hg-photo-CVD technology The Hg-photo-CVD technique, known for its use in  eveloping thin film of semiconductor materials and dielectrics has been a  resurgence of interest in view of their many applications in microelectronics. It is  established that the physico-chemical and optoelectronic material filed in this case the hydrogenated amorphous silicon (a-Si: H) are a  function of preparation conditions, including substrate temperature, the pressure of reactive gases, their speed, light intensity, temperature of reaction medium, temperature of the mercury and temperature of the post-deposition annealing.We highlight in this article which is a review of our work in this area, the conditions for optimization of key  arameters of deposition : Mercury Temperature T HG : about 50° C - substrate temperature Ts : 250 to 300 °C - Reactive gas pressure : around 1 Torr - gas flow reagent : 1 to 5 sccm (or cm3 / s) - The nominal light intensity : 10 to 20 mW/cm2, temperature of post-deposition annealing: about 300 ° C for 30 minutes. At Ts = 280 °C, the photosensitivity is optimized to a value of more than 103. In the optimal working conditions proposed, conversion of the reactive gas in silicon is streamlined and the large amount of hydrogen formed, for security reasons, become as the carrier gas for the evacuation of the gas mixture

Production d'énergie et analyse financière d’une installation photovoltaïque en Côte-d’Ivoire

One key factor for boosting economic growth in developing countries is the energetic independence of the countries. Renewable energies are well suited for such purpose even if effective dissemination of renewable energies is their production price. The energy production of solar plants is highly dependent of both sun radiation and climate data and therefore dependent of their location. This paper reports on the economic and financial calculations related to the energy production of a standard 20 kW photovoltaic plant connected to the electric network and located in Ivory Coast (Côte d Ivoire). Its economic profitability in terms of economic returns of the electricity production is calculated by using capital budgeting techniques. It is demonstrated that when photovoltaic plants are considered as economic assets, the knowledge of financial and economic characteristics of the country as well as the geographical localization of photovoltaic plants, have to be taken into account in order to assess the profitability of the investment. The Levelized Cost of the Energy generated for the photovoltaic plant during its expected time of operation (25 years) is calculated and compared with other economical parameters.Guaita Pradas, I.; Marí Soucase, B.; Boko, A. (2015). Energy production and financial analysis of photovoltaic energy plants in Ivory Coast. Afrique SCIENCE: Revue internationale des sciences et technologie. 11(2):24-34. http://hdl.handle.net/10251/60835S243411

Comparative study between CZTS and CZTSe thin layers for photovoltaic applications

A comparative study of the thin layer based on copper zinc tin sulphide Cu2ZnSnS4 (CZTS) and that based on copper zinc tin selenide Cu2ZnSnSe4 (CZTSe) was made in order to assess the structural, morphological, optical and electrical qualities. for better use in improving performance of CZTS, CZTSe or CZTSSe based solar cell. CZTS and CZTSe thin films prepared by the spray pyrolysis technique were characterized by X-ray diffraction (XRD) which confirmed their kesterite structure in the tetragonal crystal phase. In addition, the analysis of the surfaces of the thin layers with the scanning electron microscope SEM, showed compact grains, well agglomerated and of appreciable sizes. UV-visible spectroscopy measured the quality of light absorption and located the bandgap energy values between 1.16 eV for CZTSe and 1.69 eV for CZTS i.e. in the range of potential absorbers for CZTS and CZTSe based thin film solar cells

Optimisation des paramètres photovoltaïques du CIGS a l aide du simulateur AMPS-1D

[FR] Le Silicium Indium de Gallium et Cuivre (CIGS) dans sa structure chalcopyrite possède des propriétés électriques et électroniques intéressantes. Notre étude a porté sur la concentration de dopage des différentes couches constituant le CIGS et les effets des contacts avant et arrière sur les performances photovoltaïques de la cellule solaire. Nous avons fait la simulation de la variation de la concentration de dopage des différentes couches constituant le CIGS à l¿aide d¿AMPS-1D. Les effets du dopage des différentes couches constituant la cellule solaire à base de CIGS sur les paramètres photovoltaïques tel que le rendement (¿) la tension de circuit ouvert (Vco) et la densité de court-circuit(Jsc) ont été étudiés.L¿augmentation de la concentration de dopage des couches a un effet sur les performances des cellules solaires. Le plus grand rendement a été obtenu lorsqu¿on a augmenté la concentration dedopage de la couche absorbeur. L¿augmentation des conditions aux limites du contact avant diminue le rendement des cellules photovoltaïques tandis que l¿augmentation des conditions aux limites du contact arrière l¿augmente.[EN] Copper indium gallium (di) selenide (CIGS) in its chalcopyrite structure has electrical and electronic properties. Our study focused on the doping of the various layers constituting the CIGS and the effects of the front and back contacts on the photovoltaic performance of the solar cell. We simulated the variation of the doping concentration of the various layers constituting the CIGS using AMPS-1D. The effects of the doping of the various layers of the CIGS solar cell on the photovoltaic parameters such as the efficiency (¿) open circuit voltage (Vco) and the court circuit density (Jsc) have been analyzed. The increase in the doping of the layers has an effect on the performance of the solar cells. The greatest efficiency was obtained when the doping of the absorbed layer is height. The increase in the boundary conditions of the front contact decreases the efficiency of the photovoltaic cells while the increase in boundary conditions of the back contact increases.Oyedele, S.; Boko, A.; Marí, B. (2017). Optimisation des paramètres photovoltaïques du CIGS a l aide du simulateur AMPS-1D. Afrique Science. 13(2):274-283. http://hdl.handle.net/10251/101852S27428313

A Viability Approach For Management Of IEEE 802.15.4 Wireless Sensor Node Performance

The long-term use of wireless sensors node while guaranteeing a good Quality of Services (QoS) is a major challenge in wireless sensor networks. Most of the relevant solutions which exist are proposed under Mac layer level but they use an optimization technique which requires a regular update of parameters and leads to unnecessary energy consumptiom which reduces the expected liftime and QoS. So in order to adress this issue, we propose in this paper, an adaptive management of wireless sensor node resources to meet application requirements in terms of energy consumption, reliability and delay. To do this, we have used the theory of viability, which is an approach that allows controling the evolution of a system in a set of desirable states. Here we have proposed an enhanced analytical model of sensor node’s energy dynamic, and we control it based on both Mac layer parameters of the IEEE 802.15.4 standard and the packet sampling frequency. The simulation results have shown that the proposed model is more accurate and efficient as a node can send more information without violating energy, reliability and delay constraints

Techniques d'affectation flexible des ressources : caractérisation et modélisation

A l’interface entre les sciences de l'ingénieur, les sciences économiques et les sciences humaines et sociales, le génie industriel a pour but d’apporter des réponses dans les secteurs très divers de l’entreprise. Un de ces problèmes est l’ajustement permanent entre la charge de travail représentée par les travaux à réaliser et la disponibilité des ressources de l’entreprise. L’objectif de ce travail est de contribuer à la recherche d’une méthodologie d’affectation flexible des ressources humaines dans la planification des activités industrielles. Cet article est composé de deux parties qui sont complémentaires. Nous y proposons une démarche pour la modélisation de l’affectation flexible des ressources humaines en matière de planification d’activités. Cette modélisation prend en compte deux aspects de la flexibilité, liés l’un à la modulation du temps de travail, et l’autre à la diversité des tâches qui peuvent être accomplies par une ressource donnée (polyvalence). D’une part, la polyvalence des acteurs qui permettra de guider les divers choix d’affectation afin d’apprécier, les répercussions de ces choix sur les durées des tâches, et d’autre part la modulation du temps de travail qui permet aux acteurs d’avoir un plan de travail variable selon les charges de l’entreprise

Techniques d'affectation flexible des ressources : résolution par algorithme génétique monocritère

Dans cet article qui est la suite logique du premier, nous présentons une méthodologie de résolution pour trouver des solutions de la formulation mathématique. Cette méthodologie est basée sur l’utilisation des algorithmes génétiques monocritères qui permettent d’affecter aléatoirement les acteurs sur les différentes charges d’une tâche. Dans cette méthode, nous considérons que les acteurs affectés sur chaque tâche effectuent le même nombre d’heures de travail. Le nombre d’acteurs affectés se fait de manière aléatoire dans la limite du nombre total d’acteurs affectables ; c'est-à-dire, ceux qui ont une efficacité suffisante dans une compétence demandée par la tâche. A partir de ces choix, un calcul est fait pour le travail global périodique de chaque acteur ce qui permet de calculer le nombre global d’heures de l’activité et partant de là son coût

Synthesis of Perfectly Oriented MAPb0.93Cr0.07Br3 Perovskite Crystals for Thin-Film Photovoltaic Applications

[EN] Wide band gap methylammonium lead halide perovskites (CH3NH3PbX3, X=halogen; CH3NH3: MA) are interesting materials for photovoltaic applications. They have recently gained substantial attention because of their high efficiency, low cost, superior optical properties. The most attractive and representative perovskites are methylammonium lead halides (CH3NH3PbX3,) denoted as MAPbX3, X = Br, Cl, I. usually the optical and structural properties of CH3NH3PbBr3 can be adjusted by introducing other extrinsic ions such as chloride and bromide. In this work, instead of replacing the halogens I or Cl with bromine (Br) as usual, we preferred to act on the post-transition metal (Pb). To this end, we replaced lead with chromium (Cr) which is a transition metal and may have the same oxidation state (+2) as lead. MAPb0.93Cr0.07Br3 thin films were deposited on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a cubic perovskite with space group Pm3 m. The structural analysis reveals films with (110) and (220) as main peaks. Deposited films showed a strong absorbance in the UV¿vis range. The band gap values were estimated from absorbance measurements. It was found between 1.60 and 1.80 eV. SEM analysis shows a morphology with good coverage and no apparent crystal orientation.Soro, D.; Sidibé, M.; Fassinou, W.; Marí, B.; Sall, T.; Fofana, B.; Boko, A.... (2017). Synthesis of Perfectly Oriented MAPb0.93Cr0.07Br3 Perovskite Crystals for Thin-Film Photovoltaic Applications. International Journal of Innovative Research in Science, Engineering and Technology. IJIRSET (Online). 6(6):10170-10176. doi:10.15680/IJIRSET.2017.0606007S10170101766

Photodecomposition sensibilisee au mercure du monosilane (Hg-Photo-CVD) : application au depot en couches minces de silicium amorphe hydrogene (a-Si : H)

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Synthesis and characterization of kesterite Cu2ZnSn(SxSe1-x)4 thin films with low-cost for efficient solar cells

In this study, we conducted an investigation on the Cu2ZnSnS4 (CZTS) kësterite compound, which is considered an attractive material for its favorable absorption properties, making it a suitable semiconductor for photovoltaic applications. However, its market potential is limited by its low efficiency of 12.6%, primarily caused by the presence of secondary phases that act as recombination centers. Theoretically, the efficiency limit for CZTS ranges from 31% to 33%.To enhance the photovoltaic performance of CZTS, we employed a doping strategy by incorporating selenium (Se) into the Cu2ZnSn(SxSe1-x)4 film, where the sulfur-to-selenium ratio (S/Se) was optimized within the range of 0< x <1. The CZTS films were deposited onto FTO substrates using the spray pyrolysis technique, which is a simple and cost-effective method. The characterization of these films involved X-ray diffraction (XRD) and UV–visible spectroscopy analysis. Additionally, the morphology and topography of the CZTSSe layers were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Transmission electron microscopy (TEM) was also employed.The results obtained in this study indicate that CZTSSe films exhibit band gap values ranging from 1.54 eV to 1.68 eV and grain compactness, with larger agglomerated grains on the film surface when the S/Se ratio is approximately 0.5 or lower. Moreover, the resistivity measurements revealed significant variations when sulfur and selenium were combined, suggesting the influence of their composition on the electrical properties of the CZTS films