Publications of Pierre Colson
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See detailLead-free double perovskite materials for photovoltaic application
Daem, Nathan ULiege; Dewalque, Jennifer ULiege; Spronck, Gilles ULiege et al

Poster (2019, May 13)

This work consists in studying the implementation of double perovskite materials in the form of thin film and showing the effect of the deposition conditions on the structural properties (uniformity ... [more ▼]

This work consists in studying the implementation of double perovskite materials in the form of thin film and showing the effect of the deposition conditions on the structural properties (uniformity, coverage rate, roughness, thickness, crystallinity, crystallite size) and on the optoelectronic properties (light absorption, electron-hole pair generation efficiency, charge diffusion length, recombination...). Before considering ultrasonic spray pyrolysis deposition, preliminary spin-coating tests are ongoing in order to verify the formation of Cs2AgBiBr6 phase according to the protocol reported by Greul et al. (J. Mater Chem A (2017), 19972-19981). The effect of precursors concentration, thermal post-treatment (hot plate/oven, temperature/duration), antisolvent dripping, relative humidity - which are reported as critical parameters for the preparation of high efficiency lead halides perovskite solar cells - on the layer morphology have been studied. The (micro)structural properties of the layers (uniformity, coverage rate, crystallite size, crystalline phase) have been characterized by scanning electron microscopy and X-ray diffraction. To improve charge collection within the lead-free double perovskite photoactive material, we have also investigated a mesoporous TiO2 network as an electron collecting material filled by Cs2AgBiBr6. Efficiencies of 1.7 % have been reached for our best PV cells which are very promising results. [less ▲]

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See detailOpal-like CH3NH3PbI3 perovskite solar cells : effect of the 3D structuration on the conversion efficiency
Dewalque, Jennifer ULiege; Daem, Nathan ULiege; Spronck, Gilles ULiege et al

Poster (2019, May 13)

In this work, the 3D structuration of perovskite films is studied in order to highlight the effect of a periodic porous structure on the optical properties of the films (light harvesting, optical ... [more ▼]

In this work, the 3D structuration of perovskite films is studied in order to highlight the effect of a periodic porous structure on the optical properties of the films (light harvesting, optical coloration, semi-transparency…) and on the PV efficiency, in comparison with dense perovskite films usually used in planar solar cells configuration. The opal-like perovskite scaffold is obtained from templating fabrication method, with polystyrene beads as structuring agent. Five PS bead diameters are studied: 300 nm, 540 nm, 810 nm, 1.0 µm and 2.1 µm, to highlight the effect of the PS bead diameter on the optical properties of the films and on the PV efficiency. PbI2/CH3NH3I 0.7M in DMSO leads to the most covering, homogeneous and overlayer-free porous films. The PV efficiency of the corresponding cells increases with the bead diameter. A significant improvement in the PV conversion efficiency is observed thanks to the 3D structuration compared to a dense reference, due to the improvement of charge separation at the Spiro-OMeTAD/perovskite interface and thus to the reduction of charge recombination. In addition, CH3NH3PbI3 porous films prepared with 810 nm, 1000 nm and 2100 nm PS bead diameter respectively, are coloured, which is very interesting for building-integrated applications (BIPV). [less ▲]

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See detailInfluence of ZnO Surface Modification on the Photocatalytic Performance of ZnO/NiO Thin Films
Periyannan, Shanmugapriya ULiege; Manceriu, Laura ULiege; Nguyen, Ngoc Duy ULiege et al

in Catalysis Letters (2019)

Charge carrier separation is considered as a key factor in enhancing the photocatalytic process and can be maximized by mitigating surface recombination. Following this idea, the surface of zinc oxide ... [more ▼]

Charge carrier separation is considered as a key factor in enhancing the photocatalytic process and can be maximized by mitigating surface recombination. Following this idea, the surface of zinc oxide (ZnO) was modified by thermal treatment and nickel oxide (NiO) deposition. The influence of the ZnO thermal treatment and NiO deposition conditions on the ZnO surface chemistry and heterostructure interface properties were investigated by in situ X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) and correlated to the dye photodegradation efficiency. The XPS analysis confirmed a change of doping of ZnO after thermal treatment, which mainly influenced the developed band bending, and has led to an improved photocatalytic activity. For the same reason, the heterostructures based on the surface cleaned ZnO surface had higher photocatalytic efficiency than the ones based on non-cleaned ZnO. The temperature input during NiO deposition had negligible effect on the heterostructure interface properties. The photocatalytic efficiency did not follow the band bending evolution because of a dominant contribution of charge recombination across the NiO layer as indicated by PL analysis. [less ▲]

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See detailDesign of monodisperse polystyrene/polyacrylonitrile core-shell particles used as templating agents and source of carbon
Thangaraj, Vidhyadevi ULiege; Schrijnemakers, Audrey ULiege; Dewalque, Jennifer ULiege et al

Poster (2018, October 03)

In the present work, we synthesized Polystyrene (PS) and Polystyrene/polyacrylonitrile (PS/PAN) core shell particles by surfactant-free emulsion polymerization and characterized them by DLS and TEM. After ... [more ▼]

In the present work, we synthesized Polystyrene (PS) and Polystyrene/polyacrylonitrile (PS/PAN) core shell particles by surfactant-free emulsion polymerization and characterized them by DLS and TEM. After deposition of the PS/PAN particles on a surface, a TiCl4 solution was infiltrated in the interstices before thermal treatment. The carbonization of the PS core and the PAN shell led to voids and carbon in the inorganic layer, respectively. This paved the way to well-organized carbon coated porous TiO2 layers of interest in the field of electronics. [less ▲]

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See detailDispersion of conductive carbon allotropes inside Na2FePO4F particles by spray-drying
Berardo, Loris ULiege; Mahmoud, Abdelfattah ULiege; Caes, Sebastien et al

Poster (2018, October 02)

Among all phosphate based compounds, Na2FePO4F (NFPF) is identified as a promising low-cost material for Li and Na-ion batteries [2]. Beside a relatively high voltage (3.6 V vs. Li+/Li0), Na2FePO4F ... [more ▼]

Among all phosphate based compounds, Na2FePO4F (NFPF) is identified as a promising low-cost material for Li and Na-ion batteries [2]. Beside a relatively high voltage (3.6 V vs. Li+/Li0), Na2FePO4F exhibits a good theoretical capacity (~135 mAh/g) and an excellent stability of the structure during the intercalation process. However, despite these powerful advantages, the main drawback of Na2FePO4F cathode material is its low conductivity leading to mediocre cycling performance. The aim of this work is to enhance the electronic conductivity of Na2FePO4F particles by addition of carbon nanotubes (CNT) or carbon black (CB) during the spray-drying synthesis [3]. The structural, electrochemical and morphological properties of the synthesized Na2FePO4F-xCB and Na2FePO4F-xCNT (x = wt% of carbon) were investigated by various techniques in order to compare the effect of CB and CNT. [less ▲]

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See detailHeterostructured ZnO/RuO2 photocatalyst: influence of sputtering temperature on the photocatalytic and photoelectrochemical properties
Periyannan, Shanmugapriya ULiege; Manceriu, Laura ULiege; Colson, Pierre ULiege et al

Poster (2018, June 19)

Influence of thermal conditions on the performance of heterostructured ZnO/RuO2 in their photocatalytic and photoelectrochemical properties Photocatalytic materials are highly investigated due its vital ... [more ▼]

Influence of thermal conditions on the performance of heterostructured ZnO/RuO2 in their photocatalytic and photoelectrochemical properties Photocatalytic materials are highly investigated due its vital role in wide variety of applications that could help in tackling present day environmental problems. Inspite of wide and basic investigation for several decades on promising materials, the best photocatalyst is still under research. But the decades long research helped in better understanding of the materials and mechanisms involved. This led to the improvement of materials under examination from homostructured to modified materials. One of the major limiting factors of homostructured (single) photocatalyst is the fast recombination of excited charge carriers. Among several modification techniques used to enhance the lifetime of charge carriers, heterostructure formation with two different materials is very promising. Here, we report the formation of ZnO/RuO2 by involving two steps: ZnO nanorods are grown on FTO by hydrothermal method, followed by physical deposition of RuO2 (At room temperature [RT], At RT followed by Insitu-Post Annealing at 250° & At High Temperature [HT] 400°), resulting in the formation of a heterostructure. The influence of different thermal conditions on the course of RuO2 deposition has been characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS) and Photo Luminescence (PL). The crystallinity of the material and its orientation was examined by XRD. Morphological studies by SEM revealed the growth of randomly oriented ZnO nanorods on FTO, whereas images of ZnO/RuO2 resulted in no structural difference. A very thin layer of RuO2 covering the surface of ZnO nanorods was observed through TEM. This displayed the core-shell type of heterostructure formation. XPS studies of ZnO/RuO2 under varying conditions implied the shift towards lower binding energy, which indicates the bond sharing between both materials. Interface studies by step-wise deposition of RuO2 on ZnO, showed the evidence for formation of band bending between two materials, which play an important role in enhancing the charge carrier separation. PL of homostructured and heterostructured materials led to the understanding with carrier recombination process. There was evidence of significant quenching for ZnO/RuO2, compared to that of ZnO. Among ZnO/RuO2 (At RT, RT-PAd, HT) – deposition at 400° disclosed higher quenching, i.e., reduced rate of recombination. Photocatalytic and Photoelectrochemical investigations was clearly correlating to the characterizational studies, confirming the enhancement in performance with heterostructure, especially with the ZnO/RuO2 (400°). [less ▲]

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See detailInsight into the electrical properties damaging with quenching of the SnO2:F layers
Manceriu, Laura ULiege; Maho, Anthony ULiege; Labrugère, Christine et al

Conference (2018, June 18)

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See detailSpray coating as scalable deposition technique of TiO2 blocking layer to boost the perovskite solar cell performances
Schrijnemakers, Audrey ULiege; Dewalque, Jennifer ULiege; Spronck, Gilles ULiege et al

Poster (2018, February 28)

To achieve high efficiency, the blocking layer (BL) is of critical importance in perovskite solar cells. Indeed, substrate has to be covered by a dense TiO2 film to prevent short circuits in the final PV ... [more ▼]

To achieve high efficiency, the blocking layer (BL) is of critical importance in perovskite solar cells. Indeed, substrate has to be covered by a dense TiO2 film to prevent short circuits in the final PV cell. In this study, we compare the spin coating (SC) technique - commonly used for the TiO2 blocking layer deposition in solid-state methylammonium lead triiodide perovskite (MaPbI3)-based solar cells - with ultrasonic spray pyrolysis (USP). Ultrasonic spray coating is a promising non-vacuum pathway to manufacture blocking layer that can be implemented from laboratory to industrial scale. The BL microstructure is characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). Although both deposition techniques lead to similar coating thickness and structure, the cyclic voltammetry measurements highlight the higher blocking capability of the ultrasonic spray pyrolysis BL. The BLs were tested in complete solar cell devices. Performance of perovskite solar cells is discussed and related to the morphology and the conductivity of the TiO2 blocking layers. [less ▲]

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See detailOpal-like photoanodes with photonic effects in macroporous perovskite solar cells
Dewalque, Jennifer ULiege; Baron, Damien ULiege; Spronck, Gilles ULiege et al

Poster (2018, February 28)

Organic-inorganic metal halide perovskite compounds, used either in mesoscopic or planar solar cells architectures, have allowed preparing highly efficient solid-state devices (>20%). In mesoscopic solar ... [more ▼]

Organic-inorganic metal halide perovskite compounds, used either in mesoscopic or planar solar cells architectures, have allowed preparing highly efficient solid-state devices (>20%). In mesoscopic solar cells, a mesoporous TiO2 scaffold is incorporated into the cells. However, because of the small pore size compared to the wavelengths of visible light, the scaffold barely scatters light. In this work, we propose to design periodically structured TiO2 scaffold from colloidal crystal templating fabrication method. Polystyrene beads with diameters comparable to visible light wavelengths are used as structuring agent. The resulting opal-like photonic structure will strongly interact with light and increase light harvesting. The photoanode microstructure is characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). In parallel, light interaction is modeled in order to find the best compromise in terms of photonic architecture. Sunlight absorption by the solar cells is presented and discussed with dependency of pore sizes and number of opal-like layers. [less ▲]

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See detailUltrasonic spray deposition of electrochromic oxide films
Maho, Anthony ULiege; Manceriu, Laura ULiege; Colson, Pierre ULiege et al

Poster (2017, September)

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See detailHeterostructured photocatalytic material and the influence of its architecture
Periyannan, Shanmugapriya ULiege; Manceriu, Laura ULiege; Colson, Pierre ULiege et al

Conference (2017, May 22)

HETEROSTRUCTURED PHOTOCATALYTIC MATERIAL AND THE INFLUENCE OF ITS ARCHITECTURE The unending usage of fuels and polluting the water bodies around the world have consequently led to the decline of the ... [more ▼]

HETEROSTRUCTURED PHOTOCATALYTIC MATERIAL AND THE INFLUENCE OF ITS ARCHITECTURE The unending usage of fuels and polluting the water bodies around the world have consequently led to the decline of the health of environment. In order to mitigate the repercussions in future, one of the few serious environmental issues like energy and water crises are being addressed from several decades with wide research on photocatalysts and photocatalysis. A typical photocatalysis reaction involves three vital steps associated with charge kinetics: charge generation, transfer and consumption. They are interdependent and each of these steps needs to be improved to realize higher efficiencies. Recent advancements and developments in identifying the working mechanisms, synthesis techniques and characterizations have paved the way for gaining attentiveness towards structure engineering (Energy band + Surface + Interface engineering). Efforts taken towards the enhancement of structure engineering can capably improve efficiencies of the steps involved in charge kinetics. In this work, we have embraced the structure engineering for the preparation of metal oxide heterostructured films with controlled architecture, to enhance its photocatalytic properties. Heterostructured architecture of a photocatalyst, which consists in combining two different materials at the nanoscale, has always shown better performance than the homostructured metal oxide semiconductors. Despite the beneficial factors of an individual metal oxide - like favorable electronic configuration, ability to absorb light and excite the electrons- the major limiting factor is usually fast recombination of the excited charge carriers, which makes it a less performing photocatalyst. Here, we have prepared heterostructured photocatalysts composed by two metal oxide semiconductors, in order to favor charge separation in each component and thereby limit recombination. The material was prepared as supported thin films in three steps, to attain the heterostructure formation. First, one dimensional Zinc Oxide material (component I) was prepared using a two step wet chemical route on FTO substrates [Step 1 – spin coating the seeds layer; Step 2 – growing the nanorods by hydrothermal method]. The concentration of seeding solution and number of seeds layers, was varied to optimize the desired morphology before deposition of component II. This resulted in the growth of ZnO nanorods arrays with predominent normal orientation. The Nickel Oxide (component II) was deposited on top of the ZnO nanorods using the direct current sputtering method, using a Nickel target in presence of Oxygen. With component II – the oxygen partial pressure, deposition temperature and time were varied to study the influence of those parameters on the heterostructure formation as well as the photocatalytic activity. AFM analysis was done to investigate the adherence of material to the FTO surface and the roughness before and after deposition was compared. The formation of heterostructure between the two components was confirmed with the help of characterizations like XRD, SEM, and XPS. The XRD peak intensity of NiO was influenced by the rate of deposition, and the morphology by temperature during sputtering. At a lower rate of deposition, the layer thickness was reduced such that it was not visible anymore by SEM, but its presence was confirmed through XPS. Photocatalytic tests were performed with UV light source to analyze the photocatalyst’s degradation efficiency on Methylene Blue. [less ▲]

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See detailStraightforward prediction of the Ni1−xO layers stoichiometry by using optical and electrochemical measurements
Manceriu, Laura ULiege; Colson, Pierre ULiege; Maho, Anthony ULiege et al

in Journal of Physics: D Applied Physics (2017), 50

In this study, we propose a straightforward method for x determination in sub-stoichiometric nickel oxide (Ni1−xO) films prepared by ultrasonic spray pyrolysis on fluor-tin oxide (FTO) substrates by ... [more ▼]

In this study, we propose a straightforward method for x determination in sub-stoichiometric nickel oxide (Ni1−xO) films prepared by ultrasonic spray pyrolysis on fluor-tin oxide (FTO) substrates by varying the post-deposition thermal treatment. The Ni3+ concentration, the flat band potential (Φfb) and the open circuit potential (Voc) were determined by electrochemical impedance analysis in aqueous media and correlated to the transmission of Ni1−xO films. An x-ray photoelectron spectroscopy study was also performed to quantify the amount of Ni3+ in the films and compare it with the one determined by electrochemical analysis. The electrochromic behavior of the Ni1−xO films in non-aqueous electrolyte was investigated as well. With increasing Ni3+ concentration the films became more brownish and more conductive, both Voc and Φfb values increased. Calibration curves of transmission at 550 nm or open circuit potential versus carrier concentration were plotted and allowed the prediction of x in an unknown Ni1−xO sample. The Ni1−xO films characterized by the highest Ni3+ concentration have a darker colored state but lower transmission modulation, due to their reduced specific surface and increased crystallinity. [less ▲]

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See detailUltrasonic spray coating of electrochromic nanomaterials
Maho, Anthony ULiege; Manceriu, Laura ULiege; Colson, Pierre ULiege et al

Conference (2017, May)

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See detailInverse opal photoanodes: preparation and optical properties
Dewalque, Jennifer ULiege; Spronck, Gilles ULiege; Baron, Damien ULiege et al

Conference (2017, March 01)

Perovskite compounds, used either in mesoscopic or planar solar cells, have allowed preparing highly efficient solid-state devices (>20%). In this study, we propose to design photoanodes with photonic ... [more ▼]

Perovskite compounds, used either in mesoscopic or planar solar cells, have allowed preparing highly efficient solid-state devices (>20%). In this study, we propose to design photoanodes with photonic structure in order to modulate light interaction. The periodic structure of porosity could add specific optical properties likely to increase light harvesting and reduce reflexion losses. Besides, current efficiencies reported for mesoscopic perovskite solar cells using an inorganic porous scaffold are slightly lower than those reported for planar perovskite cells mainly due to issues in perovskite infiltration. The control of the porous network architecture in terms of pore organization, size and connectivity could overcome this limitation. TiO2/perovskite and perovskite-only photoanodes with an inverse opal porous structure are prepared from templating techniques, using polystyrene beads as structuring agent. The photoanode microstructure is further characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). In parallel, light interaction is modeled in order to find the best compromise in terms of photonic architecture (pore size, organization, thickness…). [less ▲]

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See detailComparison of Indium Tin Oxide and Indium Tungsten Oxide as Transparent Conductive Substrates for WO3-Based Electrochromic Devices
Maho, Anthony ULiege; Nicolay, Sylvain; Manceriu, Laura ULiege et al

in Journal of the Electrochemical Society (2017), 164(2), 25-31

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See detailWaveguide solar concentrator design with spectrally separated light
Michel, Céline ULiege; Blain, Pascal ULiege; Clermont, Lionel ULiege et al

in Solar Energy (2017), 157

In this article, we propose a new solar concentrator based on spectral splitting of sunlight. Spectral splitting has the objective to collect different spectra onto spectrally adapted solar cells for a ... [more ▼]

In this article, we propose a new solar concentrator based on spectral splitting of sunlight. Spectral splitting has the objective to collect different spectra onto spectrally adapted solar cells for a more efficient use of the Sun’s spectrum. Its combination with solar concentration makes an alternative to classical technologies. The proposed concentrator is composed of a diffractive/refractive optical element that spectrally splits and focuses the light onto a waveguide. The light is then conducted by total internal reflection towards the two specific solar cells. The optical concept and optimization of each element is presented in this paper. An adaptation for dye sensitized solar cells is performed. A geometrical factor around 5× is reached. Finally, theoretical optical efficiency, the manufacturing process and experimental testing with a collimated Sun simulator are presented. [less ▲]

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See detailSurfactant-assisted USP deposition of WO3 electrochromic thin films on various TCO-glass substrates
Maho, Anthony ULiege; Nicolay, Sylvain; Manceriu, Laura ULiege et al

Conference (2016, August 31)

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See detailImprinting superconducting vortex footsteps in a magnetic layer
Brisbois, Jérémy ULiege; Motta, Maycon; Avila Osses, Jonathan ULiege et al

in Scientific Reports (2016), 6

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit ... [more ▼]

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit cards and computer hard drives. Here we experimentally show that a similar principle can be applied for imprinting the trajectory of quantum units of flux (vortices), travelling in a superconducting film (Nb), into a soft magnetic layer of permalloy (Py). In full analogy with the magnetic drawing board, vortices act as tiny magnetic scribers leaving a wake of polarized magnetic media in the Py board. The mutual interaction between superconducting vortices and ferromagnetic domains has been investigated by the magneto-optical imaging technique. For thick Py layers, the stripe magnetic domain pattern guides both the smooth magnetic flux penetration as well as the abrupt vortex avalanches in the Nb film. It is however in thin Py layers without stripe domains where superconducting vortices leave the clearest imprints of locally polarized magnetic moment along their paths. In all cases, we observe that the flux is delayed at the border of the magnetic layer. Our findings open the quest for optimizing magnetic recording of superconducting vortex trajectories. [less ▲]

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