Preparation and Characterization of SnS thin films by Chemical Spray Pyrolysis for fabrication of solar cells

El objetivo de esta tesis es la síntesis de películas delgadas de SnS utilizando técnicas de bajo coste con el fin de fabricar células solares. Nuestra contribución radica en estudiar nuevos materiales susceptibles de ser utilizados para aplicaciones fotovoltaicas, y que puedan ser preparados con técnicas de bajo coste como la técnica de Pyrolysis de Spray Químico (CSP) y caracterizar algunos materiales elegidos para este fin como el Sulfuro de Estaño (SnS). Se han fabricado células solares a partir de la disposición de capas: Mo / SnS / Tampón / i-ZnO / ZnO: Al / Al / Metal. Las capas de buffer serían: In2S3 o CdS. En la primera etapa hemos procedido a la optimización de los parámetros de deposición de películas delgadas de SnS usando la técnica de la CSP, -Variación de la relación [S] / [Sn]. -Variación de la temperatura del substrato. -Variación de la naturaleza del sustrato utilizando sustrato como vidrio, óxido de estaño de indio (ITO) y vidrio recubierto de molibdeno. Las fuentes de productos químicos y disolventes utilizados son: - Cloruro de dihidrato dihidratado para Tin (Sn), Thiourea, Agua destilada como disolvente de la solución, Ethanol (10% de 50mL) con el fin de reducir la tensión superficial del agua que es 72 Nm-1, para permitir la dispersión de la solución depositada sobre el sustrato fácilmente. En una segunda etapa se han dopado pel¿culas delgadas de SnS con algún elemento en la tabla de Mendeleiev para modificar las propiedades f¿sicas y qu¿micas de las pel¿culas. Los elementos químicos utilizados fueron: Plata, Aluminio y Hierro. Se han utilizado varias técnicas de caracterización: - Difracción de rayos X (XRD) para la estructura cristalina de las películas - Espectroscopía Raman para la calidad de las películas - Microscopía electrónica de barrido (SEM) para morfología superficial - Microscopía de Fuerza Atómica (AFM) para topografía de superficie - Análisis dispersivo de energía de rayos X (EDAX) adjunto a SEM para la composición de la película - Espectrofotometría óptica para la transmisión y la determinación del gap - Método de 4 puntas para medición de resistividad del SnS dopado -Mott-Schottky para determinar el tipo de semiconductor y la concentración de portadores Los principales resultados obtenidos en esta tesis pueden resumirse como sigue: -Las películas delgadas mono-sulfuro (SnS) deben depositarse sobre un sustrato de vidrio con [S] / [Sn] igual a una (1) y la temperatura del sustrato igual a 350 ° C para obtener películas densas, bien cubiertas y homogéneas sin agujeros Y grietas. Distancia entre la boquilla al sustrato 25 cm, volumen pulverizado 5 ml, presión de aire 0,7 bar y velocidad de pulverización de 1,5 ml / min. - Para películas dopadas por Plata y Aluminio, todas las películas son estructura ortorrómbica con (111) como pico principal. La intensidad del pico principal aumenta cuando el porcentaje de elemento dopante aumenta en la solución inicial sin ninguna fase secundaria para el dopaje con Al y con Ag8SnS6 y Ag para el dopaje Ag. - El análisis de SEM y AFM demuestra que el elemento dopante Ag no tiene efecto en la morfología y ni en la topografía mientras que el dopaje Al actúa sobre la morfología superficial produciendo una morfología que presenta muchos agujeros para muestras dopadas de 3% a 7%. - EDAX destaca un aumento de Ag en películas cuando la cantidad de Ag aumenta en la solución con S/ Sn¿0,98 cerca de 1 al 5% de porcentaje de dopado de Ag donde como para el dopaje EDAX destaca la mejora de la estequiometría con un aumento del porcentaje de Al Atómica en películas cuando la concentración de Al aumenta en la solución inicial con S / Sn = 0, 99 al 10%. - La resistividad de las muestras dopadas con Ag y Al aumenta con la concentración de dopado y se observa un aumento del gap óptico de 1.66eV a 1.70eV para SnS dopado por Ag y SnS dopado por Al, respectivamente.ß-In2S3 thin films deposited by Chemical Spray Pyrolysis technique at different substrate temperatures (250 °C-300 °C-350 °C) showed well crystallized thin films with (0 0 12) as preferred direction perpendicular to the plane containing the surface of glass substrate. SEM images showed dense, uniform, well-covered layers that adhere well to substrates and no crack and void space were noted for all substrate temperatures. Microanalysis X confirms the presence of In and S elements with good stoichiometry after vacuum annealing for 30 minutes. Raman spectroscopy analysis confirms ß-In2S3 phase with more prominent modes after vacuum annealing. We also noted a reduction in the gap energies after annealing for films prepared at 250 °C and 350 °C substrate temperatures while for those prepared at 300 °C, the energy of the gap remains stable. Tin mono-sulfide (SnS) thin films must be deposited onto glass substrate with [S]/[Sn] ratio equal to one (1) and substrate temperature equal to 350 °C to obtained dense, well-covered, and homogeneous films without pinholes and cracks. Distance between nozzle to substrate is kept to 25cm, sprayed volume 5mL, air pressure 0.7bar and spray rate 1.5 mL/min. Films doped with Silver (Ag) and Aluminum (Al) were all orthorhombic structure with (111) as main peak. The intensity of main peak increased when the percentage of dopant element increased in the initial solution without any secondary phase for Al-doping films and with Ag8SnS6 and Ag for Ag-doping ones. SEM and AFM analysis showed that Ag-doping element had no effect in the morphology and the topography while Al-doping affected the surface morphology with "fishing net" like morphology with lots of holes for samples doped from 3% to 7%. EDS highlighted an increase of Ag in films when its amount increased in the solution with S/Sn¿0.98 near to 1 at 5% of Ag-doping percentage where as for Al-doping EDS highlighted improvement of stoichiometry with an increase of Al percentage atomic in films when Al concentration increased in the initial solution with S/Sn¿0.99 at 10%. Electrical and energy band gap measurement showed a decrease of resistivity when Ag and Al percentages increased in the solution to reach relatively low resistivity of 108¿.cm and 170¿.cm at 10% for both, and an increased of energy band gap when the Ag and Al-doping elements increased in the solution with 1.66eV and 1.70eV for SnS doped with Ag and SnS doped with Al, respectively. Spray pyrolyzed SnS thin films doped with indium were studied using various optical and electrical techniques. Structural analysis shows that all films crystallize in orthorhombic structure with (111) as a preferential direction without secondary phases. Doping of SnS layers with indium results in better morphology with increased grain size. Absorption measurements indicate dominant direct transition with energy decreasing from around 1.7 eV to 1.5 eV with increased indium supply. Apart from direct transition, an indirect one, of energy of around 1.05 eV, independent on indium doping was identified. The photoluminescence study revealed two donors to acceptor transitions between two deep defect levels and one shallower with energy of around 90 meV. The observed transitions did not depend significantly on In concentration. The conductivity measurements reveal thermal activation of conductivity with energy decreasing from around 165 meV to 145 meV with increased In content. Finally, we were investigated the J-V characteristics of FTO/CdS/SnS,FTO/ZnO/CdS/SnS, FTO/ZnO:Al/CdS/SnS, FTO/ZnO:Al/SnS and FTO/In2S3/SnS solar cells and we found that efficiencies are very low due probably to the recombination at the junction, grain boundaries, etc.L'objectiu d'aquesta tesi és la síntesi de pel·lícules primes de SnS utilitzant tècniques de baix cost per tal de fabricar cèl·lules solars amb alta eficiència. La nostra contribució rau en estudiar nous materials susceptibles de ser utilitzats per a aplicacions fotovoltaiques, i que puguin ser preparats amb tècniques de baix cost com la tècnica de Spray Piròlisis Químic (CSP) i caracteritzar alguns materials triats per a aquest fi, com ara el Sulfur de estany (SnS). S'han fabricat cèl·lules solars a partir de la disposició de capes: Mo/SnS /Tampó/i-ZnO/ZnO: Al/ Metall. Les capes de per al bufer intermèdi has sigut de In2S3 i CdS. En la primera etapa hem procedit a l'optimització dels paràmetres de deposició de pel·lícules primes de SnS usant la tècnica CSP. -Variació de la relació [S] / [Sn]. -Variació de la temperatura Ts del substrat. -Variació de la naturalesa del substrat utilitzant substrat com: vidre simple, òxid d'estany d'indi (ITO) i vidre recobert de molibdè. Les fonts de productes químics i dissolvents utilitzats han sigut; Clorur d'estany per a l'estany (Sn), thiourea per sofre (S). Aigua destil·lada com a dissolvent de la solució. Ethanol (10% de 50ml) per tal de reduir la tensió superficial de l'aigua que és 72 Nm-1, per a permetre la dispersió de la solució dipositada fàcilment sobre el substrat. En una segona etapa s'han dopat pel.lícules primes de SnS amb algun element en la taula de Mendeleiev per modificar les propietats físiques i químiques de les pel.l¿cules. Els elements químics utilitzats són: Plata (Ag+), alumini (Al3+), Ferro (Fe2+), Coure (Cu2+) i Antimoni (SB3+) com a font de nitrat de plata (AgNO3), Clorur d'alumini (AlCl3) (FeCl2·4H2O ), Clorur de Coure (CuCl2 i Clorur de Antimoni (SbCl3). S'han utilitzat diverses tècniques de caracterització: - Difracció de raigs X (XRD) per a l'estructura de les pel·lícules i cristal - Raman Spectroscopy per a la qualitat de les pel·lícules - Microscòpia electrònica de rastreig (SEM) per morfologia superficial - Microscòpia de Força Atòmica (AFM) per topografia de superfície - Anàlisi dispersiu d'energia de raigs X (EDAX) adjunt a SEM per a la composició de la pel·lícula -Espectrofotometría per a la transmissió i el mesurament de la banda d'energia utilitzant la trama de Tauc - Tècnica de punta-sonda per a mesurament de resistivitat amb dopat SnS -Mott-Schottky per determinar el tipus de semiconductor i la concentració de portadors Els principals resultats obtinguts en aquesta tesi poden resumir així: -Les pel·lícules primes mico-sulfur (SnS) han de dipositar-sobre un substrat de vidre amb [S]/[Sn] igual a una (1) i la temperatura del substrat igual a 350 °C per obtenir pel·lícules denses, ben cobertes i homogènies sense forats I esquerdes. Distància entre el filtre al substrat 25 cm, volum polvoritzat 5 ml, pressió d'aire 0,7 bar i velocitat de polvorització de 1,5 ml / min. Per pel·lícules dopades per Plata i alumini, totes les pel·lícules són estructura ortorrómbica amb (111) com pic principal. La intensitat del pic principal augmenta quan el percentatge d'element dopant augmenta en la solució inicial sense cap fase secundària per al dopatge amb Al i amb Ag8SnS6 i Ag per al dopatge Ag. L'anàlisi de SEM i AFM demostra que l'element dopant Ag no té efecte en la morfologia i la topografia mentre que el dopatge en actua sobre la morfologia superficial produint una morfologia que presenta molts forats per a mostres dopades de 3% a 7%. EDAX destaca un augment de Ag en pel·lícules quan la quantitat d'Ag augmenta en la solució amb S / Sn¿0,98 prop d'1 a 5% de percentatge de dopatge d'Ag on com per al dopatge EDAX destaca la millora de l'estequiometria amb un augment del percentatge d'al Atòmica en pel·lícules quan la concentració d'al augmenta en la solució inicial amb S / Sn = 0,99 al 10%.Sall, T. (2017). Preparation and Characterization of SnS thin films by Chemical Spray Pyrolysis for fabrication of solar cells [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/95412TESI

Tin-mono-sulfide (SnS) Thin Films Prepared by Chemical Spray Pyrolysis with Different [S]/[Sn] Ratios

[EN] SnS thin films were deposited by chemical spray pyrolysis using cost-effective and low-toxicity sources materials like tin (II) chloride dihydrate and thiourea as sources of tin and sulphur, respectively. We have studied the properties of sprayed SnS thin films with [S]/[Sn] ratios were varied from 1 to 4 in order to optimize these parameters. X-ray diffraction was used for analyzing the films structure, Raman Spectroscopy for assessing the films quality and structure, scanning electron microscope (SEM) for surface morphology and energy dispersive energy (EDS) for compositional element in samples, atomic force microscopy (AFM) for the topography of surfaces and optical spectroscopy for measuring transmittances and then deducing the band gap energies. All films obtained are polycrystalline with (111) as preferential direction for films with [S]/[Sn] ratio equals to one while for [S]/[Sn] ratios from 2 to 4 the main peak becomes (101) and the (111) peak decreases in intensity. Raman spectroscopy confirms the presence of only one SnS phase without any additional parasite secondary phases. SEM images revealed that films are well adhered onto glass surface with rounded grain. AFM confirms this result being films with [S]/[Sn] = 1 the roughest and also with the largest grain size. EDS results show an improvement of stoichiometry with the increase of the [S]/[Sn] ratio. From optical analysis, it is inferred that the band gap energy decreases from 1.83 to 1.77 eV when the [S]/[Sn] ratio changes from 2 to 4.This work was supported by Ministerio de Economia y Competitividad (ENE2016-77798-C4-2-R) and Generalitat valenciana (Prometeus 2014/044).Sall, T.; Mollar García, MA.; Marí, B. (2017). Tin-mono-sulfide (SnS) Thin Films Prepared by Chemical Spray Pyrolysis with Different [S]/[Sn] Ratios. Optical and Quantum Electronics. 49(11). https://doi.org/10.1007/s11082-017-1219-9S3864911Avellaneda, D., Nair, M.T.S., Nair, P.K.: Polymorphic tin sulfide thin films of zinc blende and orthorhombic structure by chemical deposition. J. Electrochem. Soc. 55, D517–D525 (2008)Brownson, J.R.S., Georges, C., Levy-Clement, C.: Synthesis of δ-SnS polymorph by electrodeposition. Chem. Mater. 18, 6397–6402 (2006)Chandrasekhar, H.R., Humphreys, R.G., Zwick, U., Cardona, M.: Infrared and Raman spectra of the IV-VI compounds SnS and SnSe. Phys. Rev. B 15, 2177–2183 (1977)Gao, C., Shen, H., Sun, L., Huang, H., Lu, L., Cai, H.: Preparation of SnS films with zinc blende structure by successive ionic layer adsorption and reaction method. Mater. Lett. 64, 2177–2179 (2010)Koteeswara Reddy, N., Ramesh, K., Ganesan, R., Reddy, K., Gunasekhar, K.R., Gopal, E.: Synthesis and characterization of co-evaporated tin sulphide thin films. J. Appl. Phys. A 83, 133–138 (2006)Loferski, J.J.: Theoretical considerations governing the choice of the optimum semiconductor for photovoltaic solar energy conversion. J. Appl. Phys. 27, 777–784 (1956)Malaquias, J., Fernandes, P.A., Salome, P.M.P., da Cunha, A.F.: Assessment of the potential of tin sulphide thin films prepared by sulphurization of precursors as cell absorbers. Thin Solid Films 519, 7416–7420 (2011)Mathews, N.R., Anaya, H.B.M., Cortes-Jacome, M.A., Angeles-Chavez, C., Toledo-Antonio, J.A.: Tin sulfide thin films by pulse electrodeposition: structural, morphological, and optical properties. J. Electrochem. Soc. 157, H337–H341 (2010)Reddy, K.T.R., Reddy, N.K., Miles, R.W.: Photovoltaic properties of SnS based solar cells. Sol. Energy Mater. Sol. Cells 9, 3041–3046 (2006)Sall, T., Mollar, M., Marí, B.: Substrates influences on the properties of SnS thin films deposited by chemical spray pyrolysis technique for photovoltaic applications. J. Mater. Sci. 51, 7607–7613 (2016)Sinsermsuksakul, P., Heo, J., Noh, W., Hock, A.S., Gordon, R.G.: Atomic layer deposition of tin monosulfide thin films. Adv. Energy Mater. 1, 1116–1125 (2011)Sivaramasubramaniam, R., Muhamad, M.R., Radhakrishna, S.: Optical properties of annealed tin (II) oxide in different ambients. Phys. Status Solidi (a) 136, 215–222 (1993)Ullah, H., Marí, B.: Numerical analysis of SnS based polycrystalline solar cells. Superlattices Microstruct. 72, 148–155 (2014

Substrate Influences on the Properties of SnS Thin Films Deposited by Chemical Spray Pyrolysis Technique for Photovoltaic Applications

The final publication is available at Springer via http://dx.doi.org/10.1007/s10853-016-0039-9.Herein, we report on tin monosulfide (SnS) thin films elaborated by the Chemical Spray Pyrolysis (CSP) technique onto various substrates as simple glass, ITO-, and Mo-coated glasses in order to study the influence of substrates on the physical and chemical properties of Sns thin films. Structural analysis revealed that all films crystallize in orthorhombic structure with (111) as the sole preferential direction without secondary phases. In addition, film prepared onto pure glass exhibits a better crystallization compared to films deposited onto coated glass substrates. Raman spectroscopy analysis confirms the results obtained by X-ray diffraction with modes corresponding well to SnS single crystal orthorhombic ones (47, 65, 94, 160, 186, and 219 cm21) without any additional parasite secondary phase like Sn2S3 or SnS2. Field emission scanning electron microscope revealed that all films have a cornflake-like particles surface morphology, and energy dispersive X-ray spectroscopy analysis showed the presence of sulfur and tin with a nearly stoichiometric ratio in films deposited onto pure glass. High surface roughness and large grains are observable in film deposited onto glass. From optical spectroscopy, it is inferred that band gap energy of SnS/glass and SnS/ITO were 1.64 and 1.82 eV, respectively.This work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat valenciana (Prometeus 2014/044).Sall, T.; Mollar García, MA.; Marí, B. (2016). Substrate Influences on the Properties of SnS Thin Films Deposited by Chemical Spray Pyrolysis Technique for Photovoltaic Applications. Journal of Materials Science. 51(16):7607-7613. https://doi.org/10.1007/s10853-016-0039-9S760776135116Reddy KTR, Prathap P, Miles RW (2010) Thin films of tin sulphide for application in photovoltaic solar cells in Photovoltaics. In: Tanaka H, Yamashita K (eds) Photovoltaics: developments, applications and impact. Nova Science, New York, pp 1–27Herzenberg R (1932) Rev Miner 4:33Juarez AS, Silver AT, Ortiz A (2005) Fabrication of SnS 2 /SnS heterojunction thin film diodes by plasma-enhanced chemical vapor deposition. Thin Solid Films 480–481:452–456Mathews NR, Anaya HBM, Cortes-Jacome MA, Angeles-Chavez C, Toledo-Antonio JA (2010) Tin sulfide thin films by pulse electrodeposition: structural, morphological, and optical properties. J Electrochem Soc 157:H337–H341Reddy NK, Ramesh K, Ganesan R, Reddy K, Gunasekhar KR, Gopal E (2006) Synthesis and characterization of co-evaporated tin sulphide thin films. Appl Phys A 83:133–138Ramakrishna Reddy KT, Koteswara Reddy N, Miles RW (2006) Photovoltaic properties of SnS based solar cells. Sol Energy Mater Sol Cells 90:3041–3046Ullah H, Marí B (2014) Numerical analysis of SnS based polycrystalline solar Cells. Superlattice Microst 72:148–155Avellaneda D, Nair MTS, Nair PK (2008) Polymorphic tin sulfide thin films of zinc blende and orthorhombic structures by chemical deposition. J Electrochem Soc 155:D517–D525Sinsermsuksakul P, Heo J, Noh W, Hock AS, Gordon RG (2011) Atomic layer deposition of tin monosulfide thin films. Adv Energ Mater 1:1116–1125Jeyaprakash BG, kumar RA, Kesavan K, Amalarani A (2010) Structural and optical characterization of spray deposited SnS thin film. J Am Sci 6:22–26Hibbert TG, Mahon MF, Molloy KC, Price LS, Parkin IP (2001) Deposition of tin sulfide thin films from novel, volatile (fluoroalkythiolato) tin (IV) precursors. 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Phys Rev B 15:2177–2183Revathi N, Bereznev S, Iljina J, Safonova M, Mellikov E, Volobujeva O (2013) PVD grown SnS thin films onto different substrate surfaces. J Mater Sci: Mater Electron 24:4739–4744Wang Y, Gong H, Fan BH, Hu GX (2010) Photovoltaic behavior of nanocrystalline SnS/TiO2. J Phys Chem C 114:3256–3259Tanusevski A, Poelman D (2003) Optical and photoconductive properties of SnS thin films prepared by electron beam evaporation. Sol Energy Mater Sol Cells 80:297–303Sajeesh TH, Poornima N, Kartha CS, Vijayakumar KP (2010) Unveiling the defect levels in SnS thin films for photovoltaic applications using photoluminescence technique. Phys Status Solidi A 207:1934–1939Sinsermsuksakul P, Heo J, Noh W, Hock AS, Gordon RG (2011) Atomic layer deposition of tin monosulfide thin films. Adv Energy Mater 1:116–125Bashkirov Simon A, Lazenka Vera V, Gremenok Valery F, Bente Klaus (2011) Microstructure of SnS thin films obtained by hot wall vacuum deposition method. 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SnS Thin Films Prepared by Chemical Spray Pyrolysis at Different Substrate Temperatures for Photovoltaic Applications

[EN] The preparation and analysis of morphological, structural, optical, vibrational and compositional properties of tin monosulfide (SnS) thin films deposited on glass substrate by chemical spray pyrolysis is reported herein. The growth conditions were evaluated to reduce the presence of residual phases different to the SnS orthorhombic phase. X-ray diffraction spectra revealed the polycrystalline nature of the SnS films with orthorhombic structure and a preferential grain orientation along the (111) direction. At high substrate temperature (450A degrees C), a crystalline phase corresponding to the Sn2S3 phase was observed. Raman spectroscopy confirmed the dominance of the SnS phase and the presence of an additional Sn2S3 phase. Scanning electron microscopy (SEM) images reveal that the SnS film morphology depends on the substrate temperature. Between 250A degrees C and 350A degrees C, SnS films were shaped as rounded grains with some cracks between them, while at substrate temperatures above 400A degrees C, films were denser and more compact. Energy-dispersive x-ray spectroscopy (EDS) analysis showed that the stoichiometry of sprayed SnS films improved with the increase of substrate temperature and atomic force microscopy micrographs showed films well covered at 350A degrees C resulting in a rougher and bigger grain size. Optical and electrical measurements showed that the optical bandgap and the resistivity decreased when the substrate temperature increased, and smaller values, 1.46 eV and 60 Omega cm, respectively, were attained at 450A degrees C. These SnS thin films could be used as an absorber layer for the development of tandem solar cell devices due to their high absorbability in the visible region with optimum bandgap energy.This work was supported by Ministerio de Economia y Competitividad (ENE2013-46624-C4-4-R) and Generalitat valenciana (Prometeus 2014/044).Sall, T.; Marí, B.; Mollar García, MA.; Sans-Tresserras, JÁ. (2017). SnS Thin Films Prepared by Chemical Spray Pyrolysis at Different Substrate Temperatures for Photovoltaic Applications. Journal of Electronic Materials. 46(3):1714-1719. https://doi.org/10.1007/s11664-016-5215-9S17141719463N.R. Mathews, H.B.M. Anaya, M.A. Cortes-Jacome, C. Angeles-Chavez, and J.A. Toledo-Antonio, J. Electrochem. Soc. 157, H337 (2010).N. Koteeswara Reddy, K. Ramesh, R. Ganesan, K. Reddy, K.R. Gunasekhar, and E. Gopal, Appl. Phys. A 83, 133 (2006).J.J. Loferski, J. Appl. Phys. 27, 777 (1956).K.T.R. Reddy, N.K. Reddy, and R.W. Miles, Sol. Energy Mat. Sol. C 90, 3041 (2006).C. Gao, H.L. Shen, L. Sun, H.B. Huang, L.F. Lu, and H. Cai, Mater. Lett. 64, 2177 (2010).D. Avellaneda, M.T.S. Nair, and P.K. Nair, J. Electrochem. Soc. 155, D517 (2008).J.R.S. Brownson, C. Georges, and C. Levy-Clement, Chem. Mater. 19, 3080 (2007).P. Sinsermsuksakul, J. Heo, W. Noh, A.S. Hock, and R.G. Gordon, Adv. Eng. Mat 1, 1116 (2011).T. Sall, M. Mollar, and B. Marí, J. Mater. Sci. 51, 7607 (2016).K. Otto, A. Katerski, O. Volobujeva, A. Mere, and M. Krunks, Energy Proc. 3, 63 (2011).J. Malaquias, P.A. Fernandes, P.M.P. Salomé, and A.F. da Cunha, Thin Solid Films 519, 7416 (2011).T.H. Sajeesh, A.R. Warrier, C. Sudha Kartha, and K.P. Vijayakumar, Thin Solid Films 518, 4370 (2010).M. Vasudeva Reddy, G. Sreedevi, C. Park, R.W. Miles, and K.T. Ramakrishna Reddy, Curr. Appl. Phys. 15, 588 (2015).A. Molenaar, Extended Abstracts, vol. 84-2, Pennington, N.J., 634 (1984)S. López, S. Granados, and A. Ortiz, Semicond. Sci. Technol. 11, 433 (1996).B. Cullity, Elements of X-ray Diffraction (New York: Addision-Wesley Publishing Company Inc, 1967), p. 501.G. Willeke, R. Dasbach, B. Sailer, and E. Bucher, Thin Solid Films 213, 271 (1992).H.R. Chandrasekhar, R.G. Humphreys, U. Zwick, and M. Cardona, Phys. Rev. B 15, 2177 (1977).S. Cheng and G. Conibeer, Thin Solid Films 520, 837 (2011)

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

Chemical spray pyrolysis of β-In2S3 thin films deposited at different temperatures

In2S3 thin films were deposited onto indium tin oxide-coated glass substrates by chemical spray pyrolysis while keeping the substrates at different temperatures. The structures of the sprayed In2S3 thin films were characterized by X-ray diffraction (XFD). The quality of the thin films was determined by Raman spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy were used to explore the surface morphology and topography of the thin films, respectively. The optical band gap was determined based on optical transmission measurements. The indium sulfide phase exhibited a preferential orientation in the (0, 0, 12) crystallographic direction according to the XRD analysis. The phonon vibration modes determined by Raman spectroscopy also confirmed the presence of the In2S3 phase in our samples. According to SEM, the surface morphologies of the films were free of defects. The optical band gap energy varied from 2.82 eV to 2.95 eV.This research was supported by the Generalitat Valenciana through the grant PROMETEUS 2009/2013 and the European Commission through the Nano CIS project (FP7-PEOPLE-2010-IRSES ref. 269279).Sall, T.; Marí Soucase, B.; Mollar García, MA.; Hartitti, B.; Fahoume, M. (2015). Chemical spray pyrolysis of β-In2S3 thin films deposited at different temperatures. Journal of Physics and Chemistry of Solids. 76:100-104. https://doi.org/10.1016/j.jpcs.2014.08.007S1001047

Animal trypanosomosis eliminated in a major livestock production region in Senegal following the eradication of a tsetse population

African animal trypanosomosis (AAT) was one of the main disease-related constraints to the development of intensive livestock production systems in the Niayes region of Senegal, a 30 km wide strip of land along the coast between Dakar and Saint-Louis. To overcome this constraint, the Government of Senegal initiated an area-wide integrated pest management programme combining chemical control tactics with the sterile insect technique to eradicate a population of the tsetse fly Glossina palpalis gambiensis Vanderplank, 1949 (Diptera, Glossinidae) in this area. The project was implemented following a phased conditional approach, and the target area was divided into three blocks treated sequentially. This study aims to assess the temporal dynamics of the prevalence of Trypanosoma spp. during the implementation of this programme. Between 2009 and 2022, 4,359 blood samples were collected from cattle and screened for trypanosomes using both the buffy coat and ELISA techniques, and PCR tests since 2020. The seroprevalence decreased from 18.9% (95%CI: 11.2–26.5) in 2009 to 0% in 2017–2022 in block 1, and from 92.9% (95%CI: 88.2–97) in 2010 to 0% in 2021 in block 2. The parasitological and serological data confirm the entomological monitoring results, i.e., that there is a high probability that the population of G. p. gambiensis has been eradicated from the Niayes and that the transmission of AAT has been interrupted in the treated area. These results indicate the effectiveness of the adopted approach and show that AAT can be sustainably removed through the creation of a zone free of G. p. gambiensis

Study of the effect of V-doping on the opto-electrical properties of spray-pyrolized SnS thin films

[EN] SnS is an earth-abundant material that is a potentially suitable candidate for the absorber layer in solar cells. Here spray-pyrolized SnS thin films doped with vanadium were studied using structural and opto-electrical methods. The thin films have an orthorhombic structure with a preferential (111) crystallographic direction. SnS has an indirect bandgap of around 1.05 eV, whereas doping with vanadium changes the band edge and shifts the absorption threshold to around 1.2 eV. The photoluminescence study revealed a broad peak related to the band-to-band transition of energy at around 1.2 eV and an additional sharp peak positioned at 1.17 eV related to vanadium. Additionally, a non-radiative recombination mechanism followed by hopping through band fluctuation barriers has been proposed for photoluminescence quenching at increased temperatures. The conductivity measurements reveal that conductivity weakly increases with V-doping, whereas its activation energy decreases from around 0.38 eV to 0.35 eV.This work was supported by the Minister den Economic y Competitividad (ENE2016-77798-C4-2-R) and Generalitat Valencia (Prometeus 2014/044).Urbaniak, A.; Pawlowski, M.; Marzantowicz, M.; Marí, B.; Sall, T. (2018). Study of the effect of V-doping on the opto-electrical properties of spray-pyrolized SnS thin films. Thin Solid Films. 664:60-65. https://doi.org/10.1016/j.tsf.2018.08.032S606566

A cyclogenesis index for tropical Atlantic off the African coasts

International audiencehe westward moving Soudano-Sahelian mesoscale convective systems (MCS) frequently reach and cross the Atlantic Coast. At the end of their continental route, most MCS weaken and vanish over the ocean, near the coast, while others strengthen. The latter play an important part in the genesis of some Atlantic tropical cyclones. In the present paper, following the work of Gray, an index liable to be associated with the coast-crossing MCS cyclonic evolution is built. The data used in this work are observations by the Dakar-Yoff radar, reanalyses of NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research), outgoing long wave radiation at the top of the atmosphere, and the resources of the National Hurricane Center data base. Several terms describing the variation of individual meteorological parameters are first analysed and then combined into an index of cyclogenesis or ICY. Combination of vertical vorticity at 925 hPa and potential vorticity at 700 hPa is notably found to be a good factor to discriminate between strengthening and weakening MCS over the near Atlantic. A good correlation between the ICY maximum and the beginning of the MCS cyclogenesis is observed. This index enables discrimination of the simultaneous presence of two separate cyclonic perturbations over the Atlantic. These results show that the sole variable ICY is useful to detect a cyclogenesis process in progress in a Sahelian MCS

Structural, morphological and optical properties of In2S3 thin films obtained by SILAR method

[EN] In2S3 thin films have been elaborated onto glass substrate by SILAR method at room temperature using different immersion time in the solution of cation and anion and fixing the rinsing time. The film composition, morphology and structure were investigated using energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and X-ray diffraction techniques. Optical properties, such transmission and band gap have been also analyzed. The effects of annealing on the morphological structure thin films are also described. The x-rays diffraction spectra indicated that the formed compounds are β-In2S3 polycrystalline thin films with In6S7 as second phase in sample S1 and sample S2 and no another phase in sample 3. SEM revealed homogeneous and relatively uniform films and EDAX shows sample 3 with S/In=1.44. For sample 1 and sample 2, we noted an increase of band gap when rinsing time increases.Sall, T.; Raidou, A.; Elfarrass, S.; Hartiti, B.; Marí, B.; Qachaou, A.; Fahoume, M. (2014). Structural, morphological and optical properties of In2S3 thin films obtained by SILAR method. Optical and Quantum Electronics. 46(1):247-257. doi:10.1007/s11082-013-9786-xS247257461Bhira, L., Essaidi, H., Belgacem, S., Couturier, G., Salardenne, J., Barreau, N., Bernede, J.C.: Structural and photoelectrical properties of sprayed \upbeta β - $$\text{ In }_{2}\text{ S }_{3}$$ In 2 S 3 thin films. Phys. Status Solidi A. 181, 427–435 (2000)Castelo-Gonzalez, O.A., Santacruz-Ortega, H.C., Quevedo-Lopez, M.A., Sotelo-Lerma, M.: Synthesis and characterization of $$\text{ In }_{2}\text{ S }_{3 }$$ In 2 S 3 thin films deposited by chemical bath deposition on polyethylene naphthalate substrates. J. Electron. Mater. 41, 695–700 (2012)Gorge, J., Joseph, K.S., Pradeep, B., Palson, T.I.: Reactively evaporated films of indium sulphide. Phys. Stat. Sol. (a) 106, 123–131 (1988)Marí, B., Mollar, M., Soro, D., Henríquez, R., Schrebler, R., Gómez, H.: Electrodeposition of $$\text{ In }_{2}S_{3}$$ In 2 S 3 thin films onto FTO from DMSO solution. Int. J. Electrochem. Sci. 8, 3510–3523 (2013)Mathew, M., Gopinath, M., Sudha Kartha, C., Vijayakumar, K.P., Kashiwaba, Y.: Tin doping in spray pyrolysed indium sulfide thin films for solar cell applications. Sol. Energy 84, 888–897 (2010)Pathan, H.M., Lokhande, C.D., Kulkarni, S.S., Amalnerka, D.P., Seth, T., Han, S.-H.: Some studies on successive ionic layer adsorption and reaction (SILAR) grown indium sulphide thin films. Mater. Res. Bull. 40, 1018–1023 (2005)Ramya, K., Reddy, M.V., Ramakrishna Reddy, K.T.: Characterization of Thermally Evaporated $$\text{ In }_{2}\text{ S }_{3}$$ In 2 S 3 Films for Solar Cell Application. Hindawi Publishing Corporation, Conference Papers in Energy vol. 2013, pp. 1–4 (May 2013)Sall, T., Hartiti, B., Mari, B., Miquel, M., Laanab, L., Fahoume, M.: Elaboration and characterization of $$\text{ In }_{2}\text{ S }_{3 }$$ In 2 S 3 thin films by spray pyrolysis with [S]/[In]=3 ratio. Renewable and Sustainable Energy Conference (IRSEC) 2013 International, IEEE pp. 58–62 (2013)Turan, E., Zor, M., Kul, M., Aybek, A.S., Taskopru, T.: \upalpha α - $$\text{ In }_{2}\text{ S }_{3}$$ In 2 S 3 and \upbeta β - $$\text{ In }_{2}\text{ S }_{3}$$ In 2 S 3 phases produced by SILAR technique. Philos. Mag. 92, 1716–1726 (2012)Uplane, M.D., Pawar, S.H.: Effect of substrate temperature on transport and optical properties of sprayed $$\text{ Cd }_{1-\text{ x }} \text{ Zn }_{\text{ x }}$$ Cd 1 - x Zn x S films. Solid State Commun. 46, 847–850 (1983