Publications of Pierre Colson
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See detailPorous functional materials for energy applications
Colson, Pierre ULiege; Dewalque, Jennifer ULiege; Maho, Anthony ULiege et al

Conference (2015)

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See detailPolymer Electrolytes for Mesoporous TiO2 Solid State Dye Sensitized Solar Cell
Bharwal, Anil Kumar ULiege; Fannie, Alloin; Iojoiu, Cristina et al

Poster (2015)

Dye-sensitized solar cells (DSSC) have attracted a great attention due to their low production cost and high photo-conversion efficiencies since a new type of dye-sensitized solar cell has been reported ... [more ▼]

Dye-sensitized solar cells (DSSC) have attracted a great attention due to their low production cost and high photo-conversion efficiencies since a new type of dye-sensitized solar cell has been reported by Grätzel [1, 2]. The electrolytes are one of the key components and their properties have much effect on the conversion efficiencies. An electrolyte containing a suitable redox couple plays a very important role in determining the photovoltaic characteristics and durability of DSSC. Although there is the inherent drawback of the cell due to the volatility and possible leakage problem of liquid electrolytes during the long-term out-door operation. Numerous efforts have been made to overcome this problem by replacing the liquid electrolytes with solid or quasi-solid state electrolytes composed of various polymers [3] and room temperature ionic liquids [4]. In this work, we report a new quasi-solid state polymer electrolyte based on polysiloxane consisting of imidazolium exhibiting higher ionic conductivity, good chemical, thermal and electrochemical stabilities. Three types of polymer electrolytes based on polysiloxane grafted with different ratio of imidazolium moieties and ionic liquids have been synthesized and characterized. Increasing the proportion of imidazolium moieties in polysiloxane increased the conductivity and viscosity of the polymer electrolyte respectively. The thermal stability of the polymer electrolytes is determined by thermogravimetric analysis. The porosity of the TiO2 photoanode plays a crucial role due to the requirement of excellent pore filling by the solid state electrolyte to ensure optimal interface. Therefore, TiO2 thin films with regular and large pores, designed for optimal electrolyte impregnation have been prepared using dual templating method. The techniques are derived from the classical Pluronic-templating synthesis of mesoporous TiO2 Anatase films [5]. The structural characterization of the TiO2 thin films have been done by techniques such as Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), XRD, etc.. The objective is to introduce a second population of pores to facilitate the accessibility of large species while keeping very high value of specific species. The performances of those combined components will be evaluated in assembled DSSC, with commercial dyes and transparent conductive glasses. Acknowledgements: This work is supported by Communauté de recherche académique, ARC Rhône Alpes. References [1] M. Grätzel, Journal of Photochemistry and Photobiology C 4, 2003, 145. [2] A. Hagfeldt, M. Grätzel, Accounts of Chemical Research 33, 2000, 269. [3] J. Wu, Z. Lan, J. Lin, M. Huang, S. Hao, T. Sato, S. Yin, Advanced Materials 19, 2007, 4006. [4] M.C. Kroon, W. Buijs, C.J. Peters, G.J. Witkamp, Green Chemistry 8, 2006, 241. [5] J. Zhao et al, Microporous and Mesoporous Materials 138, 2011, 200. [less ▲]

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See detailPolysiloxane Electrolytes for Mesoporous TiO2 based Solid State Dye Sensitized Solar Cell
Bharwal, Anil Kumar ULiege; Fannie, Alloin; Iojoiu, Cristina et al

Poster (2015)

Dye-sensitized solar cells (DSSC) have attracted a great attention due to their low production cost and high photo-conversion efficiencies since a new type of dye-sensitized solar cell has been reported ... [more ▼]

Dye-sensitized solar cells (DSSC) have attracted a great attention due to their low production cost and high photo-conversion efficiencies since a new type of dye-sensitized solar cell has been reported by Grätzel [1, 2]. The electrolytes are one of the key components and their properties have much effect on the conversion efficiencies. An electrolyte containing a suitable redox couple plays a very important role in determining the photovoltaic characteristics and durability of DSSC. Although there is the inherent drawback of the cell due to the volatility and possible leakage problem of liquid electrolytes during the long-term out-door operation. Numerous efforts have been made to overcome this problem by replacing the liquid electrolytes with solid or quasi-solid state electrolytes composed of various polymers [3] and room temperature ionic liquids [4]. In this work, we report a new quasi-solid state polymer electrolyte based on polysiloxane consisting of imidazolium exhibiting higher ionic conductivity, good chemical, thermal and electrochemical stabilities. Three types of polymer electrolytes based on polysiloxane grafted with different ratio of imidazolium moieties and ionic liquids have been synthesized and characterized. Increasing the proportion of imidazolium moieties in polysiloxane increased the conductivity and viscosity of the polymer electrolyte respectively. The thermal stability of the polymer electrolytes is determined by thermogravimetric analysis. The porosity of the TiO2 photoanode plays a crucial role due to the requirement of excellent pore filling by the solid state electrolyte to ensure optimal interface. Therefore, TiO2 thin films with regular and large pores, designed for optimal electrolyte impregnation have been prepared using dual templating method. The techniques are derived from the classical Pluronic-templating synthesis of mesoporous TiO2 Anatase films [5]. The structural characterization of the TiO2 thin films have been done by techniques such as Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM), XRD, etc.. The objective is to introduce a second population of pores to facilitate the accessibility of large species while keeping very high value of specific species. The performances of those combined components will be evaluated in assembled DSSC, with commercial dyes and transparent conductive glasses. [1] M. Grätzel, Journal of Photochemistry and Photobiology C 4, 2003, 145. [2] A. Hagfeldt, M. Grätzel, Accounts of Chemical Research 33, 2000, 269. [3] J. Wu, Z. Lan, J. Lin, M. Huang, S. Hao, T. Sato, S. Yin, Advanced Materials 19, 2007, 4006. [4] M.C. Kroon, W. Buijs, C.J. Peters, G.J. Witkamp, Green Chemistry 8, 2006, 241. [5] J. Zhao et al, Microporous and Mesoporous Materials 138, 2011, 200. [less ▲]

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See detailPolysiloxane based polymer Electrolytes for Mesoporous TiO2 Solid State Dye Sensitised Solar Cell
Bharwal, Anil Kumar ULiege; Fannie, Alloin; Iojoiu, Cristina et al

Poster (2015)

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See detailElucidating the opto-electrical properties of solid and hollow titania scattering layers for improvement of dye-sensitized solar cells
Thalluri, Venkata Visveswara Gopala Kris; Henrist, Catherine ULiege; Spronck, Gilles ULiege et al

in Thin Solid Films (2015)

The light scattering method has been adapted in dye-sensitized solar cells (DSCs) for optical absorption enhancement. In DSC's, particle-size of TiO2 should be inline with the scattering wavelength range ... [more ▼]

The light scattering method has been adapted in dye-sensitized solar cells (DSCs) for optical absorption enhancement. In DSC's, particle-size of TiO2 should be inline with the scattering wavelength range. Scattering particles can be used either by forming a bilayer structure with TiO2 nanocrystalline film or into the bulk of TiO2 nanocrystalline film. For improving the DSCs performances these scattering layers aim to refract/reflect the incident light by extending the traveling distance of UV-Visible/near-IR light within the dye-sensitized TiO2 nanocrystalline film. In this work, the scattering layers with two different particle-sizes (~200 nm-solid and ~400 nm-hollow) were deposited as an additional layer on the top of dye-sensitized TiO2 nanocrystalline film and the morphological properties were studied. By using various opto-electrical characterization techniques, the influence of these scattering layers for two different classes of DSCs prepared from N3 (UV-Vis) and SQ2 (near-IR) dyes were investigated. [less ▲]

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See detailLinear and nonlinear optical properties of functionalized CdSe quantum dots prepared by plasma sputtering and wet chemistry
Humbert, Christophe; Dahi, Abdellatif; Dalstein, Laetitia et al

in Journal of Colloid & Interface Science (2015), 445

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See detailInnovative materials improving energy efficiency of buildings
Dewalque, Jennifer ULiege; Denayer, Jessica ULiege; Schrijnemakers, Audrey ULiege et al

Conference (2014, July 01)

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See detailStability of templated and nanoparticles dye-sensitized solar cells : photovoltaic and electrochemical investigation of degradation mechanisms at the photoelectrode interface
Dewalque, Jennifer ULiege; Nguyen, Ngoc Duy ULiege; Colson, Pierre ULiege et al

in Electrochimica Acta (2014), 115(1), 478-486

A key issue in the commercialization of dye-sensitized solar cells is to maintain high efficiency and long lifetime. As reported in the literature, dye-sensitized solar cells are stable under visible ... [more ▼]

A key issue in the commercialization of dye-sensitized solar cells is to maintain high efficiency and long lifetime. As reported in the literature, dye-sensitized solar cells are stable under visible light soaking but thermal stress and UV exposure lead to efficiency degradation. However, all the stability studies published so far have been performed on cells whose TiO2 electrodes were prepared by tape casting or screen printing of nanoparticle pastes/inks. The present study concerns cells based on highly porous templated TiO2 electrodes, whose larger surface area could enhance the negative effects of thermal stress, light soaking and UV exposure. The long-term stability of these cells is compared with a classical nanoparticle-based cell using current-voltage measurements (I-V curves) and electrochemical impedance spectroscopy. Due to their higher active interface, templated cells are more sensitive than nanoparticle cells to UV illumination, although this can be easily solved in both cases by the use of a UV filter. The templated cells are as stable as the nanoparticle cells under visible light soaking (UV filtered). However, we showed that templated cells are more stable under thermal stress. Moreover, as evidenced by electrochemical impedance spectroscopy, templated cells show lower transfer resistance, as well as lower recombination resistance compared to nanoparticle cells. The crystallite connectivity promoted by the templating route seems to favor the electron transfers inside the porous layer. Using templated films in dye-sensitized solar cells is therefore really promising because higher conversion efficiencies are reached without promoting cell degradation. [less ▲]

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See detailPore-filling of Spiro-OMeTAD determined by Rutherford backscattering spectrometry in templated TiO2 photoelectrodes
Dewalque, Jennifer ULiege; Colson, Pierre ULiege; Thalluri, Venkata Visveswara Gopala Kris ULiege et al

in Organic Electronics (2014), 15

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials ... [more ▼]

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials. However, in solid-state dye-sensitized solar cells, optimal TiO2 films thickness is limited to a few microns allowing the adsorption of only a low quantity of photoactive dye and thus leading to poor light harvesting and low conversion efficiency. In order to overcome this limitation, high surface area templated films are investigated as alternative to nanocrystalline films prepared by doctor-blade or screen-printing. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructural properties (porosity, crystallinity) as well as impact on the dye loading and Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) solid electrolyte filling. We first report Rutherford backscattering spectrometry as an innovative non-destructive tool to characterize the hole transporting materials infiltration. Templated films show dye loading more than two times higher than nanocrystalline films prepared by doctor-blade or screen-printing and solid electrolyte infiltration up to 88%. [less ▲]

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See detailMesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior
Chatzikyriakou, Dafni ULiege; Krins, Natacha ULiege; Gilbert, Bernard ULiege et al

in Electrochimica Acta (2014), 137

The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we ... [more ▼]

The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and de-intercalation. According to chronoamperometric measurements, Li+ intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s). The electrochemical measurements (cyclic voltammetry and chronoamperometry) also showed worse reversibility for the dense film compared to the mesoporous film, giving rise to important Li+ trapping and remaining coloration of the film. Raman analysis showed that the mesoporous film provides more accessible and various W-O surface bonds for Li+ intercalation. On the contrary, in the first electrochemical insertion and de-insertion in the dense film, Li+ selectively reacts with a few surface W-O bonds and preferentially intercalates into pre-existing crystallites to form stable irreversible LixWO3 bronze. [less ▲]

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See detailSurfactant-assisted ultrasonic spray pyrolysis of nickel oxide and lithium-doped nickel oxide thin films, towards electrochromic applications
Denayer, Jessica ULiege; Bister, Geoffroy; Simonis, Priscilla et al

in Applied Surface Science (2014), 321

Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the ... [more ▼]

Lithium-doped nickel oxide and undoped nickel oxide thin films have been deposited on FTO/glass substrates by a surfactant-assisted ultrasonic spray pyrolysis. The addition of polyethylene glycol in the sprayed solution has led to improved uniformity and reduced light scattering compared to films made without surfactant. Furthermore, the presence of lithium ions in NiO films has resulted in improved electrochromic performances (coloration contrast and efficiency), but with a slight decrease of the electrochromic switching kinetics. [less ▲]

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See detailUltrasonic Spray Pyrolysis: an innovative fabrication method for electrochromic glazing
Maho, Anthony ULiege; Domercq, Benoit; Denayer, Jessica et al

Conference (2014)

Detailed reference viewed: 49 (9 ULiège)
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See detailImproved coloration contrast and electrochromic efficiency of tungsten oxide films thanks to a surfactant-assisted ultrasonic spray pyrolysis process
Denayer, Jessica ULiege; Aubry, Philippe; Bister, Geoffroy et al

in Solar Energy Materials & Solar Cells (2014), 130

Detailed reference viewed: 94 (63 ULiège)
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See detailTiO2 templated films used as photoelectrode for solid-state DSSC applications: study of the pore filling by Rutherford Backscattering Spectroscopy
Dewalque, Jennifer ULiege; Colson, Pierre ULiege; Thalluri, Venkata Visveswara Gopala Kris ULiege et al

Poster (2013, September)

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials ... [more ▼]

Liquid-state dye-sensitized solar cells can suffer from electrolyte evaporation and leakage. Therefore solid-state hole transporting materials are investigated as alternative electrolyte materials. However, in solid-state dye-sensitized solar cells, optimal TiO2 films thickness is limited to a few microns allowing the adsorption of only a low quantity of photoactive dye and thus leading to poor light harvesting and low conversion efficiency. In order to overcome this limitation, high surface area templated films are investigated as alternative to nanocrystalline films prepared by doctor-blade or screen-printing. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructural properties (porosity, crystallinity) as well as effect on the dye loading and Spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) solid electrolyte filling. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films. Besides, we have implemented Rutherford backscattering spectrometry (RBS) as an innovative non-destructive tool to characterize the hole transporting materials infiltration. Templated films show dye loading more than two times higher than nanocrystalline films prepared by doctor-blade or screen-printing and solid electrolyte infiltration up to 88%. [less ▲]

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See detailNanosphere Lithography: A Powerful Method for the Controlled Manufacturing of Nanomaterials
Colson, Pierre ULiege; Henrist, Catherine ULiege; Cloots, Rudi ULiege

in Journal of Nanomaterials (2013)

The never-ending race towards miniaturization of devices induced an intense research in the manufacturing processes of the components of those devices. However, the complexity of the process combined with ... [more ▼]

The never-ending race towards miniaturization of devices induced an intense research in the manufacturing processes of the components of those devices. However, the complexity of the process combined with high equipment costs makes the conventional lithographic techniques unfavorable for many researchers. Through years, nanosphere lithography (NSL) attracted growing interest due to its compatibility with wafer-scale processes as well as its potential to manufacture a wide variety of homogeneous one-, two-, or three-dimensional nanostructures. This method combines the advantages of both top-down and bottom-up approaches and is based on a two-step process: (1) the preparation of a colloidal crystal mask (CCM) made of nanospheres and (2) the deposition of the desired material through the mask. The mask is then removed and the layer keeps the ordered patterning of the mask interstices. Many groups have been working to improve the quality of the CCMs. Throughout this review, we compare the major deposition techniques to manufacture the CCMs (focusing on 2D polystyrene nanospheres lattices), with respect to their advantages and drawbacks. In traditional NSL, the pattern is usually limited to triangular structures. However, new strategies have been developed to build up more complex architectures and will also be discussed. [less ▲]

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See detailHigh Performance DSSC Based on Semiconducting Oxides Prepared Through Soft Chemistry Processes
Dewalque, Jennifer ULiege; Schrijnemakers, Audrey ULiege; Thalluri, Venkata Visveswara Gopala Kris ULiege et al

Conference (2013, July)

DSSCs have been reported by O’Regan and Grätzel in the early nineties as a very promising alternative to conventional photovoltaic silicon devices. Main benefits of these cells are their low cost as well ... [more ▼]

DSSCs have been reported by O’Regan and Grätzel in the early nineties as a very promising alternative to conventional photovoltaic silicon devices. Main benefits of these cells are their low cost as well as their mild manufacturing process. In most of the specific literature, DSSCs are made of TiO2 films prepared by doctor-blade or screen-printing of anatase nanoparticles paste. However, due to the random organization of the nanoparticles, pore accessibility by the dye and electrolyte could be incomplete. Moreover, some anatase crystallites could suffer from a lack of connectivity, leading to electron transfer issues. The strategy adopted by our group to improve photovoltaic efficiencies involves a templating-assisted process allowing the preparation of highly porous layers with well-ordered and accessible pores as well as improved crystallites connectivity. The main goal is to increase the film surface area and to perfectly control the mesostructure in order to maximize the adsorption of active dye and the electrolyte infiltration inside the porous network. This talk especially focuses on the templating-assisted synthesis of TiO2 and ZnO semiconducting layers used as photoelectrode in DSSCs. Besides, due to the surface area improvement as well as the perfect control of the pore organization and the pore size, the templating strategy can be an effective solution to overcome light harvesting and solid electrolyte filling limitations encountered in solid-state DSSCs. Special effort is paid to the tuning of the TiO2 and ZnO semiconducting layers mesostructure in order to match with solid-state DSSC applications. [less ▲]

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See detailTiO2 templated films used as photoelectrode for solid-state DSSC applications: study of the pore filling by Rutherford Backscattering Spectroscopy
Dewalque, Jennifer ULiege; Colson, Pierre ULiege; Thalluri, Venkata Visveswara Gopala Kris ULiege et al

Poster (2013, July)

Mesoporous anatase thin films are very promising materials to act as electrode in dye-sensitized solar cells. Randomly oriented nanocrystalline TiO2 particles are usually used to prepare photoelectrodes ... [more ▼]

Mesoporous anatase thin films are very promising materials to act as electrode in dye-sensitized solar cells. Randomly oriented nanocrystalline TiO2 particles are usually used to prepare photoelectrodes with a thickness of 10-15 µm. However, in solid-state DSSCs, TiO2 films thickness is limited to few µm allowing the adsorption of only a low quantity of photoactive dye and thus leading to a poor light harvesting and low conversion efficiencies. In order to overcome this limitation, templated-assisted dip-coating techniques are used to obtain thin films with high surface area. Moreover, templating is expected to improve the pore accessibility what would promote the solid electrolyte penetration inside the porous network, making possible efficient charge transfers. In this study, films prepared from different structuring agents are discussed in terms of microstructure properties (porosity, crystallinity) and impact on the dye loading and solid electrolyte filling. As-obtained templated films have been compared to nanocrystalline films prepared by doctor blade or screen printing as reference. Different techniques such as transmission electron microscopy (TEM), atmospheric poroellipsometry (AEP) and UV-visible absorption spectroscopy (UV-vis.) have been used to describe the microstructural features of the films. Solid electrolyte infiltration has been extensively investigated by Rutherford Backscattering Spectroscopy (RBS). Finally, templated films were evaluated as photoelectrode in solid-state DSSCs and compared to nanoparticles layers. [less ▲]

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See detailStudies on the Influence of Different Grain-sized Titania Scattering Layers for Dye Sensitized Solar Cells
Thalluri, Venkata Visveswara Gopala Kris ULiege; Henrist, Catherine ULiege; Vertruyen, Bénédicte ULiege et al

Poster (2013, July)

The efficiencies of dye sensitized solar cells (DSCs) are boosted up to 12% by NIR light harvesting dyes and with the usage of scattering layer in the device preparation.The importance of Titania ... [more ▼]

The efficiencies of dye sensitized solar cells (DSCs) are boosted up to 12% by NIR light harvesting dyes and with the usage of scattering layer in the device preparation.The importance of Titania scattering layers was studied as a part of this work. These scattering layers were prepared from two different grain-sizes (100 nm & 500 nm) for SQ2-NIR and N3-UV/Vis DSCs. The 100 nm grain-sized Titania paste was commercially supplied and 500 nm grain-sized Titania paste was prepared according to literature. The morphological and structural properties of these bigger grain-sized Titania layers were deliberated by using and Scanning Electron Microscope (SEM) and X-Ray diffraction (XRD) measurements. The influence of these bigger grain-sized Titania scattering layers in SQ2-NIR and N3-UV/Vis DSCs were expounded by using various electro-optical characterization techniques such as light I-V, electrochemical impedance spectroscopy (EIS) shown in Figure 1 and external quantum efficiency (EQE) measurements. The importance of understanding the influence of these bigger grain-sized scattering Titania layers could pave a way for future design and optimizing of DSCs for increasing the amount of light harvesting. [less ▲]

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