We report on the adsorption performances of HCN, H2S, HF, and H2 gases on Nb and Co embedded WS2 ... more We report on the adsorption performances of HCN, H2S, HF, and H2 gases on Nb and Co embedded WS2 monolayer using density functional theory calculations. The adsorption configurations, adsorption energy, charge transfer, density of state, band structure, and recovery time were studied to evaluate the possible tailoring of gas sensing properties to improve sensitivity and selectivity of the WS2 monolayer. The results show that HCN exhibits better adsorption on the Nb-embedded WS2 with an adsorption energy of -1.09 eV and charge transfer of -0.18 e, whereas H2S shows superior adsorption on the Co-embedded WS2 with an adsorption energy of -1.1 eV and charge transfer of 0.23 e. Better sensitivity and selectivity were recorded for the adsorption of the HCN and H2S on the Nb and Co-embedded WS2 monolayer respectively. At 398K, the recovery times for the two sensing systems are 54 s and 61s for Nb-embedded WS2 with HCN and Co-embedded WS2 with H2S respectively making them suitable for gas s...
According to the literature, conceptual change is a primary challenge in science education. Sever... more According to the literature, conceptual change is a primary challenge in science education. Several studies have indicated that learners use their intuitive conceptions even after science instruction. Therefore, our study aimed to create working conditions that would support learners' achievement of conceptual change. We hypothesized that integrating learners into the teaching-learning process in a collaborative setting will positively impact their performance to reflect the degree to which they achieve conceptual change. After the realization of a course respecting the official instructions and the curriculum of life and earth sciences, we proposed to the students of a public high school to pass a hybrid evaluation of this subject where we asked them to realize collaboratively in small groups, presentations of the synthesis of the course that they had received, in the form of a video capsule. This method has already been approached in other research works. The difference in thi...
Les couches minces de ZnO dopées Aluminium (AZO) ont été déposées par la technique spray pyrolysi... more Les couches minces de ZnO dopées Aluminium (AZO) ont été déposées par la technique spray pyrolysis sur des substrats de verre ordinaire préchauffés à la température de 425°C. Des solutions aqueuses de chlorure de zinc de concentration 0.1M et dopées à partir du nitrate d'aluminium ont été utilisées pour le dépôt. Le pourcentage de l'aluminium dans la solution variait de 0 à 5%. Après dépôt, les couches ont été caractérisées et l'effet de la concentration du dopage de l'aluminium sur leurs propriétés structurale, optique et électrique a été étudié. L'analyse structurale a montré que les films déposés ont cristallisé suivant la direction préférentielle (002) et que le dopage de l'aluminium avait un effet important sur l'intensité et le déplacement des pics. Les spectres de transmission montrent que les films AZnO sont transparents (~ 90%) dans les régions du proche ultraviolet et du visible. Les mesures électriques réalisées par la technique des 4 pointes a...
Our work consists in elaboration and characterization of cadmium sulfide (CdS) thin films. Indeed... more Our work consists in elaboration and characterization of cadmium sulfide (CdS) thin films. Indeed, in order to deposit a series of these films, we have adopted a simple and cheap technique, such as the chemical bath Deposition (CBD). The series of samples of CdS was deposited on glass substrates by varying the deposit bath temperature from 55 to 75 ° C and by keeping the deposition time fixed (25 min). Our investigation is focused on the understanding and study of the effect of the deposition temperature on the physical properties of the thin films to which it was referred. For this purpose, we used two characterization techniques which are: the X-ray diffraction (PANalytical X-ray diffractometer) for determining the structure of the films and also, the UV-Vis spectroscopy (UV-3101 PC-SHIMADZU double beam spectrophotometer) for determining their optical properties. Thicknesses (d) of CdS films was measured with gravimetric weight different method using a sensitive electronic microbalance and were confirmed by using a profilometer of the type KLATENCORP6. The structural characterization indicates that the structure of CdS films obtained is cubic or hexagonal with preferential orientation in accordance with the plane (111) or (002), respectively. The optical characterization shows that these films have a fairly high transparency which varies between 55 and 80% in the visible range of the optical spectrum, the optical gap value of which can reach 2.2 eV. It can be suggested that these properties make these films perfectly suitable for their use as window film in solar cells in thin films.
Les couches minces de Cu 2 ZnSnS 4 (CZTS) ont été préparées par voie chimique sol-gel et déposées... more Les couches minces de Cu 2 ZnSnS 4 (CZTS) ont été préparées par voie chimique sol-gel et déposées sur des substrats de verre par la technique de spin coating. La solution de dépôt a été faite à partir des sels de métaux de chlorure de cuivre (II) (CuCl 2), chlorure de zinc (II) (ZnCl 2), chlorure d'étain (IV) (SnCl 4), et de thiourée (CS (NH 2) 2) dissous dans un mélange d'éthanol/eau distillée comme solvant. Les études de diffraction de rayons X (DRX) ont révélées la formation d'une structure kesterite avec des pics correspondant aux directions (112), (220), (312). Le spectre Raman a indiqué la présence d'un pic kesterite principal à la position 336 cm-1 et l'existence d'un pic étrange à la position 424 cm-1 pouvant correspondre au composé binaire Cu 2 S. Les couches minces de CZTS ont montrés une transmission d'environ 39% et une absorption optique au dessus de 10 4 cm-1 avec une énergie de gap de 2.34 eV. Ainsi les films de CZTS peuvent être synthétisé...
In this work we have developed thin-film CZTS (Cu 2 ZnSnS 4 ) by "spray pyrolysis" tech... more In this work we have developed thin-film CZTS (Cu 2 ZnSnS 4 ) by "spray pyrolysis" technique on preheated glass substrates from an aqueous solution containing ions of copper, zinc, tin and sulfur at different temperatures. Then we performed structural analysis of samples prepared by different characterization methods such as X-ray diffraction (RXD), Raman microscopy, and transmission electron microscopy (SEM). Experimental results have verified that the thin films deposited CZTS are relatively uniform on the substrates. Structural analysis by X-ray diffraction showed that the deposited films are Kestrite structure with a bias in the direction with the appearance of a second phase the binary Cu 2 -xS, which is confirmed by the analysis Raman spectroscopy.
L’objectif de ce travail est d’etudier la structure et la transmission optique des couches minces... more L’objectif de ce travail est d’etudier la structure et la transmission optique des couches minces d’oxyde de zinc (ZnO). Pour ce faire, une solution sol-gel a ete preparee, puis deposee sur les substrats en verre mis en rotation a l’aide du spin-coater a la vitesse angulaire de 3000 tr.mn-1 pendant 30 s. Les couches minces ZnO subissent une densification thermique pendant 10 mn suivie d’un recuit thermique a 550°C pendant 2h. Les echantillons fabriques ont ete investis par les techniques de diffraction des rayons X (DRX), de microscopie electronique a balayage (MEB) couplee a la microanalyse (EDX) et de spectrophotometrie UV-Vis. Les resultats montrent une direction de croissance preferentielle (002) correspondant a la phase hexagonale wurtzite. Les echantillons presentent une surface homogene composee de cristallites de taille 44,48 nm et une composition chimique tres proche de la stœchiometrie (53,63 % pour l’oxygene et 46,37 % pour le zinc). La transmission optique evaluee dans l...
International Journal of Materials Science and Applications, 2021
ZnO thin films have been prepared by dip coating sol gel method using Taguchi technique. The unde... more ZnO thin films have been prepared by dip coating sol gel method using Taguchi technique. The underlying principle was to make something as little as conceivable the measure of examination and make sense of the best conditions for developing ZnO thin films with great properties. We used a trial plan of L9, with three levels (high, medium, low) and four elements (annealing temperature, precursor concentration, dip coating speed, annealing time). For each paper three sol-gel arrangements were arranged, and test is rehashed three time. We have chosen to carry out the optimization based on the gap energy calculated from the transmittance of the films obtained. Each sample was characterized with spectrophotometer. This characterization allowed us to draw the transmittance curve and to deduce the gap energy of each deposited ZnO thin film. A signal to noise and an analysis of variance (ANOVA) were used to determine the optical and electrical properties. The film that we obtained with the o...
CuInS 2 ternary films is a promising absorber material for thin film solar cells. It has recently... more CuInS 2 ternary films is a promising absorber material for thin film solar cells. It has recently attracted considerable attention due to its high photovoltaic conversion efficiency, and the opportunity to be synthesized by low-cost techniques. In this work CuInS 2 thin films have been deposited by chemical Spray pyrolysis onto glass substrate at ambient atmosphere without sulfurization. The effect of the [Cu]/[In] ration, substrate temperature and the time of spray, on the structural, chemical stoichiometry, topographical, and optical properties of CIS thin films were investigated. EDS result demonstrated that stoichiometric CuInS 2 film can be adjusted [Cu]/[In] ration. Chalcopyrite structure of this film was confirmed by XRD analysis. The near stoichiometric CuInS 2 film has the optical band gap Eg of 1.45eV.
Dans ce travail nous avons elabore des couches minces de CIS (CuInS2) par la technique de pulveri... more Dans ce travail nous avons elabore des couches minces de CIS (CuInS2) par la technique de pulverisation atomique dite « Spray pyrolysis » sur des substrats en verre prechauffes a partir de solution chimique a base de chlorure de cuivre, chlorure d’indium et la thiouree. Ensuite nous avons etudie l’effet du couple temperature du substrat sur l’elaboration du ternaire CIS en utilisant les differentes techniques de caracterisation : diffraction des rayons X (XRD), microscopie electronique de balayage (MEB), l’analyse elementaire (EDX), la transmission et spectroscopie Raman. Les resultats experimentaux obtenus ont permis de verifier que les couches de CIS sont relativement uniformes sur les substrats prechauffes a 375°C et pendant un temps de pulverisation de 90 min, l’analyse structurale par diffraction des rayons X a montre que tous les films deposes sont de structure chalcopyrite avec une orientation preferentielle selon la direction . Les mesures optiques ont montre que les couch...
We report on the adsorption performances of HCN, H2S, HF, and H2 gases on Nb and Co embedded WS2 ... more We report on the adsorption performances of HCN, H2S, HF, and H2 gases on Nb and Co embedded WS2 monolayer using density functional theory calculations. The adsorption configurations, adsorption energy, charge transfer, density of state, band structure, and recovery time were studied to evaluate the possible tailoring of gas sensing properties to improve sensitivity and selectivity of the WS2 monolayer. The results show that HCN exhibits better adsorption on the Nb-embedded WS2 with an adsorption energy of -1.09 eV and charge transfer of -0.18 e, whereas H2S shows superior adsorption on the Co-embedded WS2 with an adsorption energy of -1.1 eV and charge transfer of 0.23 e. Better sensitivity and selectivity were recorded for the adsorption of the HCN and H2S on the Nb and Co-embedded WS2 monolayer respectively. At 398K, the recovery times for the two sensing systems are 54 s and 61s for Nb-embedded WS2 with HCN and Co-embedded WS2 with H2S respectively making them suitable for gas s...
According to the literature, conceptual change is a primary challenge in science education. Sever... more According to the literature, conceptual change is a primary challenge in science education. Several studies have indicated that learners use their intuitive conceptions even after science instruction. Therefore, our study aimed to create working conditions that would support learners' achievement of conceptual change. We hypothesized that integrating learners into the teaching-learning process in a collaborative setting will positively impact their performance to reflect the degree to which they achieve conceptual change. After the realization of a course respecting the official instructions and the curriculum of life and earth sciences, we proposed to the students of a public high school to pass a hybrid evaluation of this subject where we asked them to realize collaboratively in small groups, presentations of the synthesis of the course that they had received, in the form of a video capsule. This method has already been approached in other research works. The difference in thi...
Les couches minces de ZnO dopées Aluminium (AZO) ont été déposées par la technique spray pyrolysi... more Les couches minces de ZnO dopées Aluminium (AZO) ont été déposées par la technique spray pyrolysis sur des substrats de verre ordinaire préchauffés à la température de 425°C. Des solutions aqueuses de chlorure de zinc de concentration 0.1M et dopées à partir du nitrate d'aluminium ont été utilisées pour le dépôt. Le pourcentage de l'aluminium dans la solution variait de 0 à 5%. Après dépôt, les couches ont été caractérisées et l'effet de la concentration du dopage de l'aluminium sur leurs propriétés structurale, optique et électrique a été étudié. L'analyse structurale a montré que les films déposés ont cristallisé suivant la direction préférentielle (002) et que le dopage de l'aluminium avait un effet important sur l'intensité et le déplacement des pics. Les spectres de transmission montrent que les films AZnO sont transparents (~ 90%) dans les régions du proche ultraviolet et du visible. Les mesures électriques réalisées par la technique des 4 pointes a...
Our work consists in elaboration and characterization of cadmium sulfide (CdS) thin films. Indeed... more Our work consists in elaboration and characterization of cadmium sulfide (CdS) thin films. Indeed, in order to deposit a series of these films, we have adopted a simple and cheap technique, such as the chemical bath Deposition (CBD). The series of samples of CdS was deposited on glass substrates by varying the deposit bath temperature from 55 to 75 ° C and by keeping the deposition time fixed (25 min). Our investigation is focused on the understanding and study of the effect of the deposition temperature on the physical properties of the thin films to which it was referred. For this purpose, we used two characterization techniques which are: the X-ray diffraction (PANalytical X-ray diffractometer) for determining the structure of the films and also, the UV-Vis spectroscopy (UV-3101 PC-SHIMADZU double beam spectrophotometer) for determining their optical properties. Thicknesses (d) of CdS films was measured with gravimetric weight different method using a sensitive electronic microbalance and were confirmed by using a profilometer of the type KLATENCORP6. The structural characterization indicates that the structure of CdS films obtained is cubic or hexagonal with preferential orientation in accordance with the plane (111) or (002), respectively. The optical characterization shows that these films have a fairly high transparency which varies between 55 and 80% in the visible range of the optical spectrum, the optical gap value of which can reach 2.2 eV. It can be suggested that these properties make these films perfectly suitable for their use as window film in solar cells in thin films.
Les couches minces de Cu 2 ZnSnS 4 (CZTS) ont été préparées par voie chimique sol-gel et déposées... more Les couches minces de Cu 2 ZnSnS 4 (CZTS) ont été préparées par voie chimique sol-gel et déposées sur des substrats de verre par la technique de spin coating. La solution de dépôt a été faite à partir des sels de métaux de chlorure de cuivre (II) (CuCl 2), chlorure de zinc (II) (ZnCl 2), chlorure d'étain (IV) (SnCl 4), et de thiourée (CS (NH 2) 2) dissous dans un mélange d'éthanol/eau distillée comme solvant. Les études de diffraction de rayons X (DRX) ont révélées la formation d'une structure kesterite avec des pics correspondant aux directions (112), (220), (312). Le spectre Raman a indiqué la présence d'un pic kesterite principal à la position 336 cm-1 et l'existence d'un pic étrange à la position 424 cm-1 pouvant correspondre au composé binaire Cu 2 S. Les couches minces de CZTS ont montrés une transmission d'environ 39% et une absorption optique au dessus de 10 4 cm-1 avec une énergie de gap de 2.34 eV. Ainsi les films de CZTS peuvent être synthétisé...
In this work we have developed thin-film CZTS (Cu 2 ZnSnS 4 ) by "spray pyrolysis" tech... more In this work we have developed thin-film CZTS (Cu 2 ZnSnS 4 ) by "spray pyrolysis" technique on preheated glass substrates from an aqueous solution containing ions of copper, zinc, tin and sulfur at different temperatures. Then we performed structural analysis of samples prepared by different characterization methods such as X-ray diffraction (RXD), Raman microscopy, and transmission electron microscopy (SEM). Experimental results have verified that the thin films deposited CZTS are relatively uniform on the substrates. Structural analysis by X-ray diffraction showed that the deposited films are Kestrite structure with a bias in the direction with the appearance of a second phase the binary Cu 2 -xS, which is confirmed by the analysis Raman spectroscopy.
L’objectif de ce travail est d’etudier la structure et la transmission optique des couches minces... more L’objectif de ce travail est d’etudier la structure et la transmission optique des couches minces d’oxyde de zinc (ZnO). Pour ce faire, une solution sol-gel a ete preparee, puis deposee sur les substrats en verre mis en rotation a l’aide du spin-coater a la vitesse angulaire de 3000 tr.mn-1 pendant 30 s. Les couches minces ZnO subissent une densification thermique pendant 10 mn suivie d’un recuit thermique a 550°C pendant 2h. Les echantillons fabriques ont ete investis par les techniques de diffraction des rayons X (DRX), de microscopie electronique a balayage (MEB) couplee a la microanalyse (EDX) et de spectrophotometrie UV-Vis. Les resultats montrent une direction de croissance preferentielle (002) correspondant a la phase hexagonale wurtzite. Les echantillons presentent une surface homogene composee de cristallites de taille 44,48 nm et une composition chimique tres proche de la stœchiometrie (53,63 % pour l’oxygene et 46,37 % pour le zinc). La transmission optique evaluee dans l...
International Journal of Materials Science and Applications, 2021
ZnO thin films have been prepared by dip coating sol gel method using Taguchi technique. The unde... more ZnO thin films have been prepared by dip coating sol gel method using Taguchi technique. The underlying principle was to make something as little as conceivable the measure of examination and make sense of the best conditions for developing ZnO thin films with great properties. We used a trial plan of L9, with three levels (high, medium, low) and four elements (annealing temperature, precursor concentration, dip coating speed, annealing time). For each paper three sol-gel arrangements were arranged, and test is rehashed three time. We have chosen to carry out the optimization based on the gap energy calculated from the transmittance of the films obtained. Each sample was characterized with spectrophotometer. This characterization allowed us to draw the transmittance curve and to deduce the gap energy of each deposited ZnO thin film. A signal to noise and an analysis of variance (ANOVA) were used to determine the optical and electrical properties. The film that we obtained with the o...
CuInS 2 ternary films is a promising absorber material for thin film solar cells. It has recently... more CuInS 2 ternary films is a promising absorber material for thin film solar cells. It has recently attracted considerable attention due to its high photovoltaic conversion efficiency, and the opportunity to be synthesized by low-cost techniques. In this work CuInS 2 thin films have been deposited by chemical Spray pyrolysis onto glass substrate at ambient atmosphere without sulfurization. The effect of the [Cu]/[In] ration, substrate temperature and the time of spray, on the structural, chemical stoichiometry, topographical, and optical properties of CIS thin films were investigated. EDS result demonstrated that stoichiometric CuInS 2 film can be adjusted [Cu]/[In] ration. Chalcopyrite structure of this film was confirmed by XRD analysis. The near stoichiometric CuInS 2 film has the optical band gap Eg of 1.45eV.
Dans ce travail nous avons elabore des couches minces de CIS (CuInS2) par la technique de pulveri... more Dans ce travail nous avons elabore des couches minces de CIS (CuInS2) par la technique de pulverisation atomique dite « Spray pyrolysis » sur des substrats en verre prechauffes a partir de solution chimique a base de chlorure de cuivre, chlorure d’indium et la thiouree. Ensuite nous avons etudie l’effet du couple temperature du substrat sur l’elaboration du ternaire CIS en utilisant les differentes techniques de caracterisation : diffraction des rayons X (XRD), microscopie electronique de balayage (MEB), l’analyse elementaire (EDX), la transmission et spectroscopie Raman. Les resultats experimentaux obtenus ont permis de verifier que les couches de CIS sont relativement uniformes sur les substrats prechauffes a 375°C et pendant un temps de pulverisation de 90 min, l’analyse structurale par diffraction des rayons X a montre que tous les films deposes sont de structure chalcopyrite avec une orientation preferentielle selon la direction . Les mesures optiques ont montre que les couch...
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