References of "Dewalque, Jennifer"
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See detailPhotonic management using opal-like crystals in perovskite solar cells
Lobet, Michaël ULiege; Piron, Pierre ULiege; Dewalque, Jennifer ULiege et al

Conference (2019, May 22)

Perovskite solar cells recently showed a tremendous interest among the photovoltaic community. However, little is known on the effect of light management inside PV architectures. We compare structured and ... [more ▼]

Perovskite solar cells recently showed a tremendous interest among the photovoltaic community. However, little is known on the effect of light management inside PV architectures. We compare structured and unstructured absorbing layers in order to enhance the integrated quantum efficiency. The photo-active layer is made of monolayer, bilayer or trilayer of perovskite spheres inside a TiO2 matrix. The excitation of guided resonances via Fano resonances inside the absorbing spheres enhances the integrated quantum efficiency and enables a photonic gain as high as 6.4%. Influence of sphere's radius, incident angle and incident polarization on the absorbing properties are also reported. [less ▲]

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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 detailBimodal titanium oxide photoelectrodes with tuned porosity for improved light harvesting and polysiloxane-based polymer electrolyte infiltration
Bharwal, Anil Kumar ULiege; Manceriu, Laura ULiege; Alloin, Fannie et al

in Solar Energy (2019), 178

In this article, we discuss the effect of the polysiloxane-based poly(ionic liquid) (PIL) electrolytes viscosity on the infiltration into mesoporous and bimodal TiO2 thin films with different thickness ... [more ▼]

In this article, we discuss the effect of the polysiloxane-based poly(ionic liquid) (PIL) electrolytes viscosity on the infiltration into mesoporous and bimodal TiO2 thin films with different thickness, and consequently on the DSSC performance. The mesoporous films contain small mesopores of 8–10 nm, resulted from the use of Pluronic P123 surfactant (SOFT), resulting in high surface area. The DUAL (soft/hard) templated films have unique bimodal porous structures comprising 8–10 nm mesopores and 60–70 nm macropores resulted from the use of P123 and 130 nm polystyrene beads, which encouraged the electrolyte pore infiltration and light harvesting. Electrochemical impedance spectroscopy confirms the lower charge transfer resistance of the DUAL templated TiO2 films as opposed to SOFT TiO2 electrodes which corresponds to higher DSSC efficiency, despite having lower dye adsorption thanks to the improved PIL electrolyte infiltration within larger pores. The addition of ionic liquids to PIL significantly lowers the viscosity, increases the ionic conductivity and I3 − diffusion rate, resulting in noticeable improvement in photovoltaic performance in both SOFT and DUAL templated photoanodes for all the observed thickness. [less ▲]

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See detailTuning bimodal porosity in TiO2 photoanodes towards efficient solid-state dye-sensitized solar cells comprising polysiloxane-based polymer electrolyte
Bharwal, Anil Kumar; Manceriu, Laura ULiege; Alloin, Fannie et al

in Microporous and Mesoporous Materials (2019), 273

This article describes a cell architecture that achieves enhanced light harvesting with less dye quantity while simultaneously improving the performance of the polysiloxane-based solid-state dye ... [more ▼]

This article describes a cell architecture that achieves enhanced light harvesting with less dye quantity while simultaneously improving the performance of the polysiloxane-based solid-state dye-sensitized solar cells (DSSCs). We report the synthesis of bimodal mesoporous anatase TiO2 films by a dual templating approach, combining a block-copolymer template (Pluronic P123) and polystyrene nanospheres (PS) as soft and hard templates, respectively. The AFM and TEM analysis of TiO2 films revealed a mixture of mesoporous and macroporous morphology in which dual porosity is generated by combustion of soft and hard templates. The size of the macropores was varied by employing PS beads with different diameters (62, 130 and 250 nm). The influence of the macropore size on the dye loading and pore infiltration is the main purpose of this article. The bimodal porosity leads to increased light scattering due to enhanced optical path length, and better pore infiltration of the polysiloxane electrolyte is achieved. The amount of dye uptake by the dual films is lower than that of soft films because the large pore size reduces the total surface area. The optimum bimodal structure was obtained when combining P123 surfactant and the 130 nm PS beads leading to the lowest charge transfer resistance and a high efficiency for DSSCs is reported with both liquid and polymer electrolytes. Even if the dye uptake was lower, the photovoltaic performance has been maintained and improved in some devices. The open circuit voltage and fill factor were improved, owing to a successful joining of different effects i.e. increased light harvesting, facile electrolyte penetration and reduced charge recombination. [less ▲]

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See detailA colloidal approach to prepare binder and crack-free TiO2 multilayer coatings from particulate suspensions: application in DSSCs
González, Zoilo; Yus, Joaquin; Sanchez-Herencia, Antonio Javier et al

in Journal of the European Ceramic Society (2019), 39

Well-compacted and crack-free TiO⁠2 multilayer coatings have been manufactured from a colloidal approach based on the preparation of particulate suspensions for DSSC. The study of the suspension ... [more ▼]

Well-compacted and crack-free TiO⁠2 multilayer coatings have been manufactured from a colloidal approach based on the preparation of particulate suspensions for DSSC. The study of the suspension parameters to optimize dispersion and stabilization of the TiO⁠2 nanoparticle in the liquid media as well as a thermal stabilization step between the layers have been defined as two key points in the processing method to obtain interconnected microstructures, free of defects and heterogeneities, that prevent the application of an additional scattering layer or any kind of specific or clean conditions during deposition. The sintering process at low temperature, 450⁰C, has allowed obtaining open microarchitectures avoiding the complete densification and favoring the dye adsorption. A thickness of 12.8 μm resulted in a successful dye loading of 4.52×10⁠−10 mol·mm⁠−2 and a photoefficiency of 5.7%, both in the range of the others particulate systems. EIS measurements were also made to study the transfer charge phenomena. [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 detailLight-harvesting capabilities of dielectric sphere multilayers
Baron, Damien ULiege; Dewalque, Jennifer ULiege; Henrist, Catherine ULiege et al

in Proceedings of SPIE: The International Society for Optical Engineering (2018, March), 10541

Self-assembled synthetic opals are suitable for integration into solution-processed thin film solar cells. In this work, finite-difference time-domain simulations are carried out to tailor optical ... [more ▼]

Self-assembled synthetic opals are suitable for integration into solution-processed thin film solar cells. In this work, finite-difference time-domain simulations are carried out to tailor optical properties of monolayer and multilayers of semiconductor spheres to trap light when these structures are incorporated into thin film solar cells. In particular, architectures in which spheres are filled with a photoactive material and embedded in a lower refractive index medium are examined. Based on spectra and field intensity maps, this study demonstrates that opal-like photonic crystals obtained from colloidal templates and filled with light-absorbing material can significantly harvest light by exploiting photonic band resonances. [less ▲]

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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 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 detailPhotonic photoanode for macroporous perovskite solar cells
Baron, Damien ULiege; Dewalque, Jennifer ULiege; Henrist, Catherine ULiege et al

Poster (2017, March 01)

Organic-inorganic metal halide perovskite solar cells (PSCs) have reached power conversion efficiencies over 20%. Two archetypal PSC architectures are reported in the literature: mesoporous and planar ... [more ▼]

Organic-inorganic metal halide perovskite solar cells (PSCs) have reached power conversion efficiencies over 20%. Two archetypal PSC architectures are reported in the literature: mesoporous and planar PSCs. In the former one, a mesoporous TiO2 scaffold is incorporated into the cell. Because sizes of the mesopores are typically small compared to wavelengths of visible light, the scaffold barely scatters light. In this work, we propose to periodically structure a porous TiO2 scaffold incorporating pores with diameters comparable to wavelengths of visible light thanks to the use of colloidal crystal templating fabrication method. The resulting TiO2 scaffold filled with perovskite will constitute an opal-like photonic crystal incorporated in the solar cell, which will strongly interact with light. Through Finite Difference Time Domain (FDTD) simulations, we demonstrate that the photonic crystal induces resonances that can be exploited to modulate light harvesting in the macroporous TiO2 layer. Sunlight absorption by the PSC will be presented and discussed with dependency of pore sizes and number of opal layers. [less ▲]

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See detailSurfactant-assisted ultrasonic spray pyrolysis of hematite mesoporous thin films
Henrist, Catherine ULiege; Toussaint, Caroline ULiege; De Vroede, Jordan et al

in Microporous and Mesoporous Materials (2016), 221

Mesoporous crystalline hematite is a material difficult to prepare by soft-templating with conventional techniques, because of its high crystallization temperature associated to the crystal-to-crystal ... [more ▼]

Mesoporous crystalline hematite is a material difficult to prepare by soft-templating with conventional techniques, because of its high crystallization temperature associated to the crystal-to-crystal goethiteto-hematite phase transition. In a previous work, it has been reported that with very careful calcination steps, it is possible to prepare mesoporous hematite films with the spin-coating technique. However, with less conventional techniques such as surfactant-assisted ultrasonic spray pyrolysis, the deposition usually leads to non-porous oxide films or to films with interstitial porosity. In this work, we demonstrate for the first time the proof-of-concept of block-copolymer templating of hematite thin films by the ultrasonic spray pyrolysis technique. Despite the fast thermal decomposition during spray deposition, a regular, monodisperse packing of spherical pores is observed after deposition on pre-heated substrates (250 C) and after a careful post-annealing step at 470 C. Moreover, with the use of a silica scaffold, we successfully preserved porosity up to a temperature as high as 800 C. These films are highly crystalline and they are composed by randomly oriented nanocrystallites with sizes as small as 25 nm. Furthermore, we show that the crystallization evolution with temperature is influenced by the presence of the templating agent and also by the preparation technique. [less ▲]

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See detailInnovative semiconducting oxide materials reducing the energy footprint of buildings
Dewalque, Jennifer ULiege; Maho, Anthony ULiege; Spronck, Gilles ULiege et al

Conference (2015, October 26)

In the current energy context, many efforts are devoted to the reduction of the energy footprint of buildings. To meet this challenge, the LCIS-GREENMAT laboratory developes a front edge research in the ... [more ▼]

In the current energy context, many efforts are devoted to the reduction of the energy footprint of buildings. To meet this challenge, the LCIS-GREENMAT laboratory developes a front edge research in the field of advanced materials associated to energy and environment, including structured materials for dye-sensitized solar cells (DSSCs) and electrochromic coatings. 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 to prepare highly porous layers with well-ordered and accessible pores as well as improved crystallites connectivity. This talk especially focuses on the templating-assisted synthesis of TiO2 and ZnO semiconducting layers used as photoelectrode in DSSCs. Due to the surface area improvement as well as the perfect control of the pore organization and the pore size, the templating strategy is an effective solution to maximize the adsorption of active dye and the electrolyte infiltration inside the porous network. Besides, in the last few years, there has been increasing interest in electrochromic glazing due to its potential use as an energy-efficient component for buildings, as it could reduce considerably their CO2 emission by decreasing their energy consumption up to 30%. The crucial issues of such devices are the durability, the coloration efficiency and the reversibility upon coloration and bleaching of the electrochromic layers. In order to improve the performances of those electrochromic films, we have investigated a surfactant-assisted deposition process for WO3 layer and the insertion of lithium in the NiO layer. All films have been deposited on FTO glass substrates by ultrasonic spray pyrolysis (USP), which is a low-cost alternative to industrial vacuum processes for manufacturing high quality thin films. The presence of lithium ions in nickel oxide films has shown improved coloration efficiency compared to the undoped films. The higher active surface of surfactant-assisted tungsten oxide films has led to higher reversibility and coloration contrast. [less ▲]

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See detailTiO2 templated films used as photoelectrode for solid-state DSSC applications: Study of the solid electrolyte infiltration by Rutherford Backscattering Spectrometry
Dewalque, Jennifer ULiege; Colson, Pierre ULiege; Mathis, François et al

Poster (2015, May 10)

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

Conference (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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