Simulating competitive egress of noncircular pedestrians

We present a numerical framework to simulate pedestrian dynamics in highly competitive conditions by means of a force-based model implemented with spherocylindrical particles instead of the traditional, symmetric disks. This modification of the individuals' shape allows one to naturally reproduce recent experimental findings of room evacuations through narrow doors in situations where the contact pressure among the pedestrians was rather large. In particular, we obtain a power-law tail distribution of the time lapses between the passage of consecutive individuals. In addition, we show that this improvement leads to new features where the particles' rotation acquires great significance

Cellules solaires à colorant tout solide composées d'une électrode de TiO 2 à porosité hiérarchisée et d'un électrolyte polyliquide ionique à matrice polysiloxane

DSSC is a 3rd generation photovoltaic technology with potential to economically harvest and efficiently convert photons to electricity. Full solid state-DSSC based on solid polymer electrolyte prevents the solvent leaking and evaporation during cell fabrication and operation, which will effectively prolong the cell life time. However, it suffers from low ionic conductivity and poor pore infiltration. The present thesis is dedicated to the concomitant development of polysiloxane-based polymer electrolytes on one side, and TiO2 photoanodes with tuned porosity on the other side, and their incorporation in solid-state dye-sensitised solar cell (ss-DSSCs), with the aim to improve their photovoltaic efficiency and the long term stability. To best of our knowledge, DSSCs comprising bimodal TiO2 layers and polysiloxane electrolytes have never been reported. The ionic conductivity and tri-iodide diffusion coefficient of the polysiloxane-based poly(ionic) liquids (PILs) were largely improved by adding of ionic liquids (ILs) or et hylene carbonate (EC), achieving ionic conductivities of 10−4 -10−3 S cm−1. The DSSCs fabricated with the optimized electrolytes showed efficiencies up to 6%, with long term stability for 250 days. Bimodal TiO2 films with dual porosity (meso- and macro-porosity) were fabricated by spin-coating, by using soft and hard templating. The dual templated films benefit from increased pore size while maintaining high surface area for dye adsorption. Bimodal films were shown to be more efficient when tested with polymer electrolytes, having comparable efficiencies with liquid electrolyte when in DSSCs, despite lower dye uptake. This thesis brings a significant contribution to the field of DSSCs as efficient and stable solar cells were prepared from newly synthesized polymer electrolytes and bimodal films.IDS Funma

Polymer electrolytes and adapted mesoporous TiO2 for Solid State Dye Sensitized Solar

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 will be prepared using templating-assisted dip-coating methods. The objective of the present work is to develop in parallel the best formulation of polymer-based electrolyte and a highly porous TiO2 photo anode. 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

Polysiloxane Electrolytes for Mesoporous TiO2 based Solid State Dye Sensitized Solar Cell

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

Polymer Electrolytes for Mesoporous TiO2 based Solid State Dye Sensitized Solar Cell

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

Polymer Electrolytes for Mesoporous TiO2 Solid State Dye Sensitized Solar Cell

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

Remarkable 8.3% efficiency and extended electron lifetime towards highly stable semi-transparent iodine-free DSSCs by mitigating the in-situ triiodide generation

International audienceAchieving highly stable and efficient dye-sensitized solar cells (DSSCs) remains a major challenge for future industrial development. In the present work, a series of ionic conductors, such as ionic liquids (ILs), polysiloxane-based poly(ionic liquid)s (PILs), and their blends are employed as electrolytes in quasi-solid-state DSSCs. In particular, we study the effect of PILs ionic functionality interaction with the ILs and ethylene carbonate (EC) on the photovoltaic performance of DSSCs with and without iodine (I2). Omitting I2 from the electrolytes in fabricated DSSCs enhances both Voc and Jsc due to the reduced charge recombination and extended effective electron lifetime. We confirm through Raman spectroscopy that in I2-free DSSCs, the in-situ generated tri-iodides (I3−) ions are sufficient enough to complete the reaction mechanism. Additionally, the I2-free DSSCs exhibit enhanced transparency, encouraging our efforts towards BIPV suitable applications. When plasticized with EC, the ionic conductivities of the highly functionalized I2-free PIL-based DSSCs exceeds 10−3 S cm−1 at 30 °C, giving record PCE of 8.3% and 9.1% under standard (1 sun) and modest (0.3 sun) illumination, respectively. These devices also show excellent long-term stability, retaining about 84% of their initial efficiency after 26 months

Printability of (Quasi-)Solid Polysiloxane Electrolytes for Online Dye-Sensitized Solar Cell Fabrication

peer reviewedDye-sensitized solar cells (DSSCs) are a very promising solution as remote sustainable low power sources for portable electronics and Internet of Things (IoT) applications due to their room-temperature and low-cost fabrication, as well as their high efficiency under artificial light. In addition, new achievements in developing semitransparent devices are driving interest in their implementation in the building sector. However, the main obstacle towards the large-scale exploitation of DSSCs mainly concerns their limited long-term stability triggered by the use of liquid electrolytes. Moreover, the device processing generally involves using a thick adhesive separator layer and vacuum filling or injection of the liquid polymer electrolyte between the two electrodes, a method that is difficult to scale up. This review summarizes the advances made in the design of alternative (quasi-)solid polymer electrolytes, with a focus on polysiloxane-based poly(ionic liquid)s. Their behavior in full DSSCs is presented and compared in terms of power generation maximization, advantages and shortcomings of the different device assembly strategies, as well as polymer electrolyte-related processing limitations. Finally, a fair part of the manuscript is allocated to the assessment of liquid and gel polymer electrolyte printability, particularly focusing on polysiloxane-based electrolytes. Spray, blade (slot-dye), screen and inkjet printing technologies are envisaged considering the polymer electrolyte thermophysical and rheological properties, as well as DSSC processing and operating conditions