PhD
Sébastien Forissier. Fabrication and characterization of down-conversion materials in thin films for photovoltaic applications. PhD thesis, École doctorale IMEP-2, Université de Grenoble, September 2012. PhD manuscript (in french). [ bib | PDF | http ]
Structural and luminescence properties of rare-earth-doped (thulium, terbium and ytterbium) thin films of yttrium oxide and titanium oxide were studied as a down-converting layer from near-UV to infrared for integration in solar cells to improve their yield. These thin films were synthesized by chemical vapor deposition at atmospheric pressure with organo-metallic precursors and assisted by aerosol (aerosol assisted MOCVD). The thin films were partially crystallized as deposited (400°C in the anatase phase for TiO2 , 540°C in the cubic phase for Y2O3). After annealing the crystallization is greatly improved and the rare-earth ion luminescence is obtained in both oxide matrices. The thulium emits in a large band centered around 800 nm and the ytterbium at 980 nm. The terbium emits mainly in the visible range. Excitation spectra showed that the photon absorption occurs in the matrix. In the TiO2 matrix a transfer rate from Tm to Yb of 20 % was measured for doping of 0,8 % for both rare-earth, which corresponds to the quenching limit. The overall measured yield is low, we showed that the probable reasons were the thin films’ lack of absorption to obtain the excitation of the sensitizer ion and a low efficiency of luminescence and down-conversion processes.
Keywords: CVD, thin films, TiO2, Y2O3, Tm, Yb, Tb, Down-conversion
Sébastien Forissier. Élaboration et caractérisation de couches de conversion de longueur d'onde pour le photovoltaïque., September 2012. PhD defense (in french). [ bib | PDF ]
Les cellules photovoltaïques ont un rendement théorique limité par l'adéquation entre le semi-conducteur et le spectre solaire. Ces travaux visent à améliorer le rendement des cellules en modifiant le spectre solaire incident sur la cellule par conversion de longueur d'onde, en absorbant dans le domaine du proche ultraviolet pour émettre dans le proche infrarouge. La conversion est recherchée grâce à des terres rares trivalentes (Yb, Tm, Tb) en matrice dioxyde de titane et yttria. Les couches minces ont été synthétisées par MOCVD assistée par aérosol à pression atmosphérique. Après optimisation des paramètres de dépôt les films sont partiellement cristallisés et leurs propriétés cristallines et optiques sont améliorées par traitement thermique. Les propriétés optiques des couches minces obtenues ont montré la luminescence des différents dopants terres rares via une large absorption dans l'ultraviolet liée à la matrice.
This work was mainly done in the LMGP (Grenoble, France) and partly in the LPCML (Lyon, France).
Personal Bibliography
Jean-Luc Deschanvres, Sébastien Forissier, Alexandre Philip, Carmen Jimenez, Hervé Roussel, and Mircea Modreanu. Characterization of Tm and Yb doped yttria thin films grown by aerosol assisted MOCVD. In EMRS Spring Meeting, Strasbourg (France), May 2012. talk. [ bib ]
In order to enhance the photovoltaic cell efficiency, in this study we aim to modify the solar spectrum by down conversion to better meet the silicon's bandgap. As down-converter thin films our work deals with thulium and ytterbium-doped yttrium oxide. Concerning near UV and blue wavelength region of the solar spectrum, Thulium will acts as sensitizer and ytterbium as emitter in near IR. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as yttrium acetylacetonate, thulium and ytterbium tetramethylheptanedionate solved in different solvents. As host matrix, yttria has received particular attention due to its high refractive index, large band gap, physical and chemical stability as well as a rather low phonon energy. As revealed by FTIR and spectroscopic IR ellipsometry, organic residues are incorporated in the film related to the deposition temperature used. A subsequent annealing step provides elimination of the organic residues and has an influence on the luminescence properties of the layer. The properties of as-deposited and annealed films where investigated including XRD, SEM , ellipsometry ( UV- visible and IR), FTIR , emission and life time measurements.
Jean-Luc Deschanvres, Sébastien Forissier, Rached Salhi, Elisabeth Payrer, Alexandre Philip, Carmen Jimenez, Hervé Roussel, Ramzi Maalej, Mohieddine Fourrati, Antoine Guile, Antonio Pereira, and Bernard Moine. Growth and characterization of luminescent rare earth doped transparent thin films for solar spectrum conversion. In EMRS Spring Meeting, Strasbourg (France), May 2012. talk. [ bib ]
The use of rare earth ions to convert photons to different wavelengths is well-known from a wide range of applications (e.g. fluorescent tubes, lasers). Recently, a new potential application has emerged: the use of rare earth ions for spectral conversion in solar cells. The main energy loss in photovoltaic cell is related to the so-called spectral mismatch: low energy photons are not absorbed by a solar cell while high energy photons are not used efficiently. In order to enhance the photovoltaic cell efficiency, in this study we aim to modify the solar spectrum by up or down conversion process to better meet the silicon's bandgap. As down-converter thin films our work deals with thulium and ytterbium-doped titania or yttria oxide. Concerning near UV and blue wavelength region of the solar spectrum, Thulium will acts as sensitizer and ytterbium as emitter in near IR. As up converter Erbium and Ytterbium doped thin films are studied. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such tetramethylheptanedionate solved in different solvents. As host matrix, yttria and titania have received particular attention due to its high refractive index, large band gap, physical and chemical stability as well as a rather low phonon energy. The properties of as-deposited and annealed films were investigated by XRD, SEM, ellipsometry, FTIR and are discussed related to the luminescent properties (emission and life time).
Sébastien Forissier, Jean-Luc Deschanvres, and Bernard Moine. Couches minces pour la conversion de longueur d'onde pour le photovoltaïque, March 2012. lab seminar (in french). [ bib | PDF ]
Sébastien Forissier, Hervé Roussel, Patrick Chaudouet, Antonio Pereira, Jean-Luc Deschanvres, and Bernard Moine. Thulium and ytterbium-doped titanium oxide thin films deposited by ultrasonic spray pyrolysis. Journal of Thermal Spray Technology, 21:1263-1268, 2012. article. [ bib | DOI | PDF | http ]
Thin films of thulium and ytterbium-doped titanium oxide were grown by metal-organic spray pyrolysis deposition from titanium(IV)oxide bis(acetylacetonate), thulium(III)tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and ytterbium(III)tris(acetylacetonate). Deposition temperatures have been investigated from 300°C to 600°C. Films have been studied regarding their crystalline and doping quality. Structural and composition characterisations of TiO2 :Tm,Yb were performed by electron microprobe, X-ray diffraction and Fourier transform infrared spectroscopy. The deposition rate can reach 0.8 μm/h. The anatase phase of TiO2 was obtained after synthesis at 400°C and over. Organic contamination at low deposition temperature is eliminated by annealing treatments.
Keywords: CVD, thulium, ytterbium, titanium oxide, thin film
Sébastien Forissier, Antoine Guille, Hervé Roussel, Carmen Jimenez, Odette Chaix, Antonio Pereira, Jean-Luc Deschanvres, and Bernard Moine. Thulium/praseodymium and ytterbium-doped titanium dioxyde thin films deposited by MOCVD. In XX International Materials Research Congress (IMRC), Cancún (Mexico), August 2011. talk. [ bib | PDF ]
In this study we aim to modify the solar spectrum to better meet the silicon's bandgap. This could be achieved either by photoluminescence up-converting devices, or down-converting devices. As down-converter thin films our work deals with thulium and ytterbium-doped titanium dioxide. Thulium will acts as sensitizer and ytterbium as emitter. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as titanium dioxide acetylacetonate, thulium and ytterbium tetramethylheptanedionate solved in different solvents. Different deposition conditions have been studied on silicon substrates, depending on temperature, dopant concentrations (…). The films are synthesised in the anatase phase above a deposition temperature of 400°C. Further annealing is required to exhibit luminescence and eliminate organic remnants of the precursors. The physicochemical and luminescent properties of the deposited films were analysed versus the different deposition parameters and annealing conditions. We showed that absorbed light is re-emitted by the ytterbium 2F5/2-2F7/2 transition at 980 nm and by a thulium 3F4-3H6 transition band around 800 nm under 330 nm excitation. Decay time measurements confirmed the energy transfer between thulium an ytterbium. Because the 980 nm emission of Yb3+ is matched with the band gap of crystalline Si, and the emission of Tm3+ is within its absorption range the phosphors are a good candidate for silicon-based solar cells.
Sébastien Forissier, Hervé Roussel, Carmen Jimenez, Odette Chaix, Antonio Pereira, Amina Bensalah-Ledoux, Jean-Luc Deschanvres, and Bernard Moine. Thulium and ytterbium-doped titanium oxide thin films deposited by MOCVD. In EMRS Spring Meeting, Nice (France), May 2011. poster. [ bib | PDF ]
In this study we aim to modify the solar spectrum to better meet the silicon's bandgap. This could be achieved either by photoluminescence up-converting devices, or down-converting devices. As down-converter thin films our work deals with thulium and ytterbium-doped titanium dioxide. Thulium will acts as sensitizer and ytterbium as emitter. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as titanium dioxide acetylacetonate, thulium and ytterbium tetramethylheptanedionate solved in different solvents. On silicon substrates different deposition conditions have been studied, depending on temperature, dopant concentrations (…). Adherent films have been obtained in the deposition temperatures range from 300°C to 600°C. The deposition rate varies in the 0.1-1 µm/h range. The films are synthesised in the anatase phase above a deposition temperature of 400°C. Further annealing is required to exhibit luminescence and eliminate organic remnants of the precursors. The physicochemical and luminescent properties of the deposited films were analysed versus the different deposition parameters and annealing conditions. We showed that absorbed light in the near-UV blue range is re-emitted by the ytterbium at 980nm and by a thulium band around 800nm.
Sébastien Forissier, Hervé Roussel, Carmen Jimenez, Odette Chaix, Antonio Pereira, Amina Bensalah-Ledoux, Jean-Luc Deschanvres, and Bernard Moine. Thulium and ytterbium-doped titania thin films deposited by MOCVD. Energy Procedia, 10(0):192 - 196, 2011. article. [ bib | DOI | PDF | http ]
In this study we synthesized thin films of titanium oxide doped with thulium and/or ytterbium to modify the incident spectrum on the solar cells. This could be achieved either by photoluminescence up-converting devices, or downconverting devices. As down-converter thin films our work deals with thulium and ytterbium-doped titanium dioxide. Thulium and ytterbium will act as sensitizer and emitter, respectively. The rare-earth doped thin films are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as titanium dioxide acetylacetonate, thulium and ytterbium tetramethylheptanedionate solved in different solvents. These films have been deposited on silicon substrates under different deposition conditions (temperature and dopant concentrations for example). Adherent films have been obtained for deposition temperatures ranging from 300°C to 600°C. The deposition rate varies from 0.1 to 1μm/h. The anatase phase is obtained at substrate temperature above 400°C. Further annealing is required to exhibit luminescence and eliminate organic remnants of the precursors. The physicochemical and luminescent properties of the deposited films were analyzed versus the different deposition parameters and annealing conditions. We showed that absorbed light in the near-UV blue range is re-emitted by the ytterbium at 980nm and by a thulium band around 800nm.
Keywords: CVD ; thulium; ytterbium; down-conversion; thin film; titanium oxide; photovoltaic
Jean-Luc Deschanvres, Sébastien Forissier, Antonio Peireira, Bernard Moine, Germain Rey, Céline Ternon, and Daniel Bellet. Élaboration de matériaux innovants en couches minces par MOCVD pour les cellules solaires de troisième génération. In Matériaux 2010, Nantes (France), October 2010. talk. [ bib ]
Sébastien Forissier. Formats ouverts et logiciels libres, July 2010. lab seminar (in french). [ bib | PDF ]
Qui n'a pas connu quelqu'un en recherche d'un chargeur de téléphone spécifique, ni transpiré au moment de lancer sa présentation powerpoint sur un autre poste que le sien ? Les formats, physiques et informatiques, sont présents partout, indispensables clés des véhicules de l'information. Les formats et les logiciels sont étroitement liés car les premiers sont crées et lus par les seconds, et le format revêt une grande importance lorsque l'information devra être transmise ou traitée avec un logiciel différent de celui de création.
Sébastien Forissier, Hervé Roussel, Carmen Jimenez, Odette Chaix, Antonio Pereira, Amina Bensalah-Ledoux, Christine Martinet, Olivier Raccurt, Jean-Luc Deschanvres, and Bernard Moine. Thulium/praseodymium and ytterbium-doped titanium dioxyde thin films deposited by MOCVD. In EMRS Spring Meeting, Strasbourg (France), June 2010. poster. [ bib | PDF ]
The efficiency of solar cells is limited by the Shockley-Queisser limit but this limit could be bypassed if we modify the solar spectrum to better meet the semiconductor's bandgap. This could be achieved either by photoluminescence, up-converting devices, or down-converting devices. As down-converter thin films, this paper deals with praseodymium and ytterbium-doped titanium dioxide. Praseodymium acts as sensitizer and ytterbium as emitter. Thin film are deposited by aerosol-assisted MOCVD using organo-metallic precursors such as titanium dioxide acetylacetonate, praseodymium and ytterbium tetramethylheptanedionate solved in different solvents. Different deposition conditions have been studied, depending on temperature, dopant concentrations (…) on silicon substrates. Deposition temperatures have been investigated from 300°C to 600°C. The deposition rate varies in the 0.1-1 µm/h range. At low temperature organic ligand residue are incorporated in the deposited film according to FTIR spectrometry. This contamination is eliminated by post-annealing treatments. The physicochemical and luminescent properties of the deposited films were analysed versus the different deposition parameters and annealing conditions.
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