The Experts below are selected from a list of 18552 Experts worldwide ranked by ideXlab platform
Michael Grätzel - One of the best experts on this subject based on the ideXlab platform.
-
a stable blue photosensitizer for color palette of dye sensitized solar cells reaching 12 6 efficiency
Journal of the American Chemical Society, 2018Co-Authors: Shaik Mohammed Zakeeruddin, Peng Wang, Hoi Nok Tsao, Yameng Ren, Danyang Sun, Yiming Cao, Yi Yuan, Michael GrätzelAbstract:We report a blue dye, coded as R6, which features a polycyclic aromatic hydrocarbon, 9,19-dihydrobenzo[1′,10′]phenanthro[3′,4′:4,5]thieno[3,2-b]benzo[1,10]phenanthro[3,4-d]thiophene, coupled with a diarylamine electron donor and 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid acceptor. Dye R6 displays a brilliant sapphire color in a sensitized TiO2 mesoporous film with a Co(II/III) tris(bipyridyl)-based Redox Electrolyte. The R6 based dye-sensitized solar cell achieves an impressive power conversion efficiency of 12.6% under standard air mass 1.5 global, 100 mW cm–2, and shows a remarkable photostability.
-
Influence of Redox Electrolyte on the device performance of phenothiazine based dye sensitized solar cells
New Journal of Chemistry, 2018Co-Authors: Reda M. El-shishtawy, Yiming Cao, Jean-david Decoppet, Fatimah A. M. Al-zahrani, Sher Bahadar Khan, M. S. Al-ghamdi, Basma G. Alhogbi, Abdullah M. Asiri, Mohammed Zakeeruddin, Michael GrätzelAbstract:We designed and synthesized a metal-free organic sensitizer based on phenothiazine as the core moiety for application in dye-sensitized solar cells (DSCs). The structure of the donor–π–bridge–acceptor (D–π–A) dye 3-(5-(7-((E)-3,4,5-trimethoxystyryl)-10-octyl-10H-phenothiazin-3-yl)thiophen-2-yl)-2-cyanoacrylic acid (TMPTZT) has tri-methoxy phenyl as a donor segment on a phenothiazine core and cyanoacrylic acid as an acceptor group. In this study, we investigated the influence of iodide/triiodide and Co(bpy)32+/3+ complexes as Redox Electrolytes on the DSC device performance. The maximal monochromatic incident photon to current conversion efficiency (IPCE) reached a value of 70%. The solar light to electrical energy conversion efficiency of the devices with a volatile solvent based iodide/triiodide Electrolyte reached up to 5.1% at AM 1.5G illumination, whereas the devices with Co(bpy)32+/3+ and ionic liquid Electrolytes showed efficiencies of 4.9% and 4.5%, respectively. The DSC devices were characterized using charge extraction and Voc decay techniques to understand the difference in the photovoltaic performance of this metal free organic dye with these three types of Redox Electrolytes.
-
A Redox-Flow Electrochromic Window
ACS applied materials & interfaces, 2015Co-Authors: James R. Jennings, Michael Grätzel, M. Zakeeruddin, Wei Yang Lim, Qing WangAbstract:A low-cost electrochromic (EC) window based on a Redox-flow system that does not require expensive transparent conductive oxide (TCO) substrates is introduced and demonstrated for the first time. An aqueous I3–/I– Redox Electrolyte is used in place of a TCO to oxidize/reduce a molecular layer of an EC triphenylamine derivative that is anchored to a mesoporous TiO2 scaffold on the inner faces of a double-paned window. The Redox Electrolyte is electrochemically oxidized/reduced in an external two-compartment cell and circulated through the window cavity using an inexpensive peristaltic pump, resulting in coloration or decoloration of the window due to reaction of the Redox solution with the triphenylamine derivative. The absorption characteristics, coloration/decoloration times, and cycling stability of the prototype EC window are evaluated, and prospects for further development are discussed.
-
High efficiency porphyrin sensitized mesoscopic solar cells
Organic Photovoltaics XV, 2014Co-Authors: Fabrizio Giordano, M. Zakeeruddin, Joël Teuscher, Michael GrätzelAbstract:Dye-Sensitized Solar Cells (DSSC) represents a reliable technology, ready for the market and able to compete with silicon solar cells for specific fields of application. Porphyrin dyes allow reaching high power conversion efficiency in conjunction with cobalt Redox Electrolytes due to larger open circuit potentials. The bigger size of the cobalt complexes compared to standard iodide/triiodide Redox couple hampers its percolation through the meso-porous TiO2 network, thus impairing the regeneration process. In case of porphyrin dyes mass transport problems in the Electrolyte need to be carefully handled, due to the large size of the sensitizing molecule and the bulky cobalt complexes. Herein we report the study of structural variations on porphyrin sensitizers and their influence on the DSSC performance with cobalt based Redox Electrolyte.
-
influence of the counter electrode on the photovoltaic performance of dye sensitized solar cells using a disulfide thiolate Redox Electrolyte
Energy and Environmental Science, 2012Co-Authors: Julian Burschka, Livain Breau, Benoît Marsan, Shaik Mohammed Zakeeruddin, Vincent Brault, Shahzada Ahmad, Mohammad Khaja Nazeeruddin, Michael GrätzelAbstract:Strong scientific interests focus on the investigation of iodine-free Redox couples for their application in dye-sensitized solar cells (DSCs). Recently, a disulfide/thiolate-based Redox Electrolyte has been proposed as a valuable alternative to the conventional I3−/I− system due to its transparent and non-corrosive nature. In the work presented herein, we systematically studied the influence of different counter electrode materials on the photovoltaic performance of DSCs employing this promising organic Redox Electrolyte. Our investigations focused on understanding the importance of electrocatalytic activity and surface area of the electroactive material on the counter electrode, comparing the conventional platinum to cobalt sulfide (CoS) and poly(3,4-ethylenedioxythiophene) (PEDOT). Electrochemical Impedance Spectroscopy has been used to study in detail the interfacial charge transfer reaction at the counter electrode. By using a high surface area PEDOT-based counter electrode, we finally achieved an unprecedented power conversion efficiency of 7.9% under simulated AM1.5G solar irradiation (100 mW cm−2) which, to the best of our knowledge, represents the highest efficiency that has so far been reported for an organic Redox couple.
Daekyu Kim - One of the best experts on this subject based on the ideXlab platform.
-
Asymmetric tin–vanadium Redox Electrolyte for hybrid energy storage with nanoporous carbon electrodes
Sustainable Energy & Fuels, 2017Co-Authors: Juhan Lee, Benjamin Krüner, Nicolas Jäckel, Aura Tolosa, Daekyu Kim, Simon Fleischmann, Marco Zeiger, Volker PresserAbstract:In recent decades, Redox-active Electrolytes have been applied in stationary energy storage systems, benefitting from Faradaic reactions of the Electrolyte instead of the electrode material. One of the challenging tasks is to balance the Redox activities between the negative and positive electrode. As a possible solution, a mixed Electrolyte with vanadyl and tin sulfate was previously suggested; however, a low power performance is a great challenge to be overcome. Here, we found that the origin of the poor power performance in the mixture Electrolyte system (vanadium complex and tin solution) is the reduction of the pore volume at the positive electrode via irreversible tin dioxide formation. To prevent the latter, we introduce a hybrid energy storage system exhibiting both battery-like and supercapacitor-like features via asymmetric Redox Electrolytes at the microporous activated carbon electrodes; SnF2 solution as anolyte and VOSO4 as catholyte. By employing an anion exchange membrane, the irreversible SnO2 formation at the positive electrode is effectively suppressed; thus, an asymmetric 1 M SnF2|3 M VOSO4 system provides a high maximum specific power (3.8 kW kg−1 or 1.5 kW L−1), while still exhibiting a high maximum specific energy up to 58.4 W h kg−1 (23.4 W h L−1) and a high cycling stability over 6500 cycles.
-
tin vanadium Redox Electrolyte for battery like energy storage capacity combined with supercapacitor like power handling
Energy and Environmental Science, 2016Co-Authors: Benjamin Krüner, Juhan Lee, Aura Tolosa, Daekyu Kim, Sethuraman SathyamoorthiAbstract:We introduce a high performance hybrid electrochemical energy storage system based on an aqueous Electrolyte containing tin sulfate (SnSO4) and vanadyl sulfate (VOSO4) with nanoporous activated carbon. The energy storage mechanism of this system benefits from the unique synergy of concurrent electric double-layer formation, reversible tin Redox reactions, and three-step Redox reactions of vanadium. The hybrid system showed excellent electrochemical properties such as a promising energy capacity (ca. 75 W h kg−1, 30 W h L−1) and a maximum power of up to 1.5 kW kg−1 (600 W L−1, 250 W m−2), exhibiting capacitor-like galvanostatic cycling stability and a low level of self-discharging rate.
-
high performance hybrid energy storage with potassium ferricyanide Redox Electrolyte
ACS Applied Materials & Interfaces, 2016Co-Authors: Juhan Lee, Soumyadip Choudhury, D Weingarth, Daekyu Kim, Volker PresserAbstract:We demonstrate stable hybrid electrochemical energy storage performance of a Redox-active Electrolyte, namely potassium ferricyanide in aqueous media in a supercapacitor-like setup. Challenging issues associated with such a system are a large leakage current and high self-discharge, both stemming from ion Redox shuttling through the separator. The latter is effectively eliminated when using an ion exchange membrane instead of a porous separator. Other critical factors toward the optimization of a Redox-active Electrolyte system, especially Electrolyte concentration and volume of Electrolyte, have been studied by electrochemical methods. Finally, excellent long-term stability is demonstrated up to 10 000 charge/discharge cycles at 1.2 and 1.8 V, with a broad maximum stability window of up to 1.8 V cell voltage as determined via cyclic voltammetry. An energy capacity of 28.3 Wh/kg or 11.4 Wh/L has been obtained from such cells, taking the nonlinearity of the charge–discharge profile into account. The power ...
Juhan Lee - One of the best experts on this subject based on the ideXlab platform.
-
High Electrochemical Seawater Desalination Performance Enabled by an Iodide Redox Electrolyte Paired with a Sodium Superionic Conductor
2019Co-Authors: Juhan Lee, Pattarachai Srimuk, Rafael L. Zornitta, Mesut Aslan, Layla B. Mehdi, Volker PresserAbstract:In recent years, a wealth of new desalination technologies based on reversible electrochemical Redox reactions has emerged. Among them, the use of Redox-active Electrolytes is highly attractive due to the high production rate and energy efficiency. Yet, these technologies suffer from the imperfect permselectivity of polymer membranes. Our present work demonstrates the promising desalination performance of a sodium superionic conductor (NASICON) for selective removal of sodium against iodide in a half-cell configuration consisting of an activated carbon electrode in aqueous 600 mM NaI solution. For feedwater with aqueous 600 mM NaCl, the desalination cell exhibited a stable performance over a month with more than 400 operation cycles with the aid of high sodium permselectivity of the NASICON membrane against iodide (99.9–100%). The cell exhibited a maximum sodium removal capacity of 69 ± 4 mg/g (equivalent to the NaCl salt uptake capacity of 87 ± 4 mg/g) with a charge efficiency of 81 ± 3%
-
Asymmetric tin–vanadium Redox Electrolyte for hybrid energy storage with nanoporous carbon electrodes
Sustainable Energy & Fuels, 2017Co-Authors: Juhan Lee, Benjamin Krüner, Nicolas Jäckel, Aura Tolosa, Daekyu Kim, Simon Fleischmann, Marco Zeiger, Volker PresserAbstract:In recent decades, Redox-active Electrolytes have been applied in stationary energy storage systems, benefitting from Faradaic reactions of the Electrolyte instead of the electrode material. One of the challenging tasks is to balance the Redox activities between the negative and positive electrode. As a possible solution, a mixed Electrolyte with vanadyl and tin sulfate was previously suggested; however, a low power performance is a great challenge to be overcome. Here, we found that the origin of the poor power performance in the mixture Electrolyte system (vanadium complex and tin solution) is the reduction of the pore volume at the positive electrode via irreversible tin dioxide formation. To prevent the latter, we introduce a hybrid energy storage system exhibiting both battery-like and supercapacitor-like features via asymmetric Redox Electrolytes at the microporous activated carbon electrodes; SnF2 solution as anolyte and VOSO4 as catholyte. By employing an anion exchange membrane, the irreversible SnO2 formation at the positive electrode is effectively suppressed; thus, an asymmetric 1 M SnF2|3 M VOSO4 system provides a high maximum specific power (3.8 kW kg−1 or 1.5 kW L−1), while still exhibiting a high maximum specific energy up to 58.4 W h kg−1 (23.4 W h L−1) and a high cycling stability over 6500 cycles.
-
tin vanadium Redox Electrolyte for battery like energy storage capacity combined with supercapacitor like power handling
Energy and Environmental Science, 2016Co-Authors: Benjamin Krüner, Juhan Lee, Aura Tolosa, Daekyu Kim, Sethuraman SathyamoorthiAbstract:We introduce a high performance hybrid electrochemical energy storage system based on an aqueous Electrolyte containing tin sulfate (SnSO4) and vanadyl sulfate (VOSO4) with nanoporous activated carbon. The energy storage mechanism of this system benefits from the unique synergy of concurrent electric double-layer formation, reversible tin Redox reactions, and three-step Redox reactions of vanadium. The hybrid system showed excellent electrochemical properties such as a promising energy capacity (ca. 75 W h kg−1, 30 W h L−1) and a maximum power of up to 1.5 kW kg−1 (600 W L−1, 250 W m−2), exhibiting capacitor-like galvanostatic cycling stability and a low level of self-discharging rate.
-
high performance hybrid energy storage with potassium ferricyanide Redox Electrolyte
ACS Applied Materials & Interfaces, 2016Co-Authors: Juhan Lee, Soumyadip Choudhury, D Weingarth, Daekyu Kim, Volker PresserAbstract:We demonstrate stable hybrid electrochemical energy storage performance of a Redox-active Electrolyte, namely potassium ferricyanide in aqueous media in a supercapacitor-like setup. Challenging issues associated with such a system are a large leakage current and high self-discharge, both stemming from ion Redox shuttling through the separator. The latter is effectively eliminated when using an ion exchange membrane instead of a porous separator. Other critical factors toward the optimization of a Redox-active Electrolyte system, especially Electrolyte concentration and volume of Electrolyte, have been studied by electrochemical methods. Finally, excellent long-term stability is demonstrated up to 10 000 charge/discharge cycles at 1.2 and 1.8 V, with a broad maximum stability window of up to 1.8 V cell voltage as determined via cyclic voltammetry. An energy capacity of 28.3 Wh/kg or 11.4 Wh/L has been obtained from such cells, taking the nonlinearity of the charge–discharge profile into account. The power ...
-
Sub-micrometer Novolac-Derived Carbon Beads for High Performance Supercapacitors and Redox Electrolyte Energy Storage.
ACS applied materials & interfaces, 2016Co-Authors: Benjamin Krüner, Juhan Lee, Nicolas Jäckel, Aura Tolosa, Volker PresserAbstract:Carbon beads with sub-micrometer diameter were produced with a self-emulsifying novolac–ethanol–water system. A physical activation with CO2 was carried out to create a high microporosity with a specific surface area varying from 771 (DFT) to 2237 m2/g (DFT) and a total pore volume from 0.28 to 1.71 cm3/g. The carbon particles conserve their spherical shape after the thermal treatments. The controllable porosity of the carbon spheres is attractive for the application in electrochemical double layer capacitors. The electrochemical characterization was carried out in aqueous 1 M Na2SO4 (127 F/g) and organic 1 M tetraethylammonium tetrafluoroborate in propylene carbonate (123 F/g). Furthermore, an aqueous Redox Electrolyte (6 M KI) was tested with the highly porous carbon and a specific energy of 33 W·h/kg (equivalent to 493 F/g) was obtained. In addition to a high specific capacitance, the carbon beads also provide an excellent rate performance at high current and potential in all tested Electrolytes, which...
Benjamin Krüner - One of the best experts on this subject based on the ideXlab platform.
-
Asymmetric tin–vanadium Redox Electrolyte for hybrid energy storage with nanoporous carbon electrodes
Sustainable Energy & Fuels, 2017Co-Authors: Juhan Lee, Benjamin Krüner, Nicolas Jäckel, Aura Tolosa, Daekyu Kim, Simon Fleischmann, Marco Zeiger, Volker PresserAbstract:In recent decades, Redox-active Electrolytes have been applied in stationary energy storage systems, benefitting from Faradaic reactions of the Electrolyte instead of the electrode material. One of the challenging tasks is to balance the Redox activities between the negative and positive electrode. As a possible solution, a mixed Electrolyte with vanadyl and tin sulfate was previously suggested; however, a low power performance is a great challenge to be overcome. Here, we found that the origin of the poor power performance in the mixture Electrolyte system (vanadium complex and tin solution) is the reduction of the pore volume at the positive electrode via irreversible tin dioxide formation. To prevent the latter, we introduce a hybrid energy storage system exhibiting both battery-like and supercapacitor-like features via asymmetric Redox Electrolytes at the microporous activated carbon electrodes; SnF2 solution as anolyte and VOSO4 as catholyte. By employing an anion exchange membrane, the irreversible SnO2 formation at the positive electrode is effectively suppressed; thus, an asymmetric 1 M SnF2|3 M VOSO4 system provides a high maximum specific power (3.8 kW kg−1 or 1.5 kW L−1), while still exhibiting a high maximum specific energy up to 58.4 W h kg−1 (23.4 W h L−1) and a high cycling stability over 6500 cycles.
-
tin vanadium Redox Electrolyte for battery like energy storage capacity combined with supercapacitor like power handling
Energy and Environmental Science, 2016Co-Authors: Benjamin Krüner, Juhan Lee, Aura Tolosa, Daekyu Kim, Sethuraman SathyamoorthiAbstract:We introduce a high performance hybrid electrochemical energy storage system based on an aqueous Electrolyte containing tin sulfate (SnSO4) and vanadyl sulfate (VOSO4) with nanoporous activated carbon. The energy storage mechanism of this system benefits from the unique synergy of concurrent electric double-layer formation, reversible tin Redox reactions, and three-step Redox reactions of vanadium. The hybrid system showed excellent electrochemical properties such as a promising energy capacity (ca. 75 W h kg−1, 30 W h L−1) and a maximum power of up to 1.5 kW kg−1 (600 W L−1, 250 W m−2), exhibiting capacitor-like galvanostatic cycling stability and a low level of self-discharging rate.
-
Sub-micrometer Novolac-Derived Carbon Beads for High Performance Supercapacitors and Redox Electrolyte Energy Storage.
ACS applied materials & interfaces, 2016Co-Authors: Benjamin Krüner, Juhan Lee, Nicolas Jäckel, Aura Tolosa, Volker PresserAbstract:Carbon beads with sub-micrometer diameter were produced with a self-emulsifying novolac–ethanol–water system. A physical activation with CO2 was carried out to create a high microporosity with a specific surface area varying from 771 (DFT) to 2237 m2/g (DFT) and a total pore volume from 0.28 to 1.71 cm3/g. The carbon particles conserve their spherical shape after the thermal treatments. The controllable porosity of the carbon spheres is attractive for the application in electrochemical double layer capacitors. The electrochemical characterization was carried out in aqueous 1 M Na2SO4 (127 F/g) and organic 1 M tetraethylammonium tetrafluoroborate in propylene carbonate (123 F/g). Furthermore, an aqueous Redox Electrolyte (6 M KI) was tested with the highly porous carbon and a specific energy of 33 W·h/kg (equivalent to 493 F/g) was obtained. In addition to a high specific capacitance, the carbon beads also provide an excellent rate performance at high current and potential in all tested Electrolytes, which...
Shozo Yanagida - One of the best experts on this subject based on the ideXlab platform.
-
Influence of doped anions on poly(3,4-ethylenedioxythiophene) as hole conductors for iodine-free solid-state dye-sensitized solar cells.
Journal of the American Chemical Society, 2008Co-Authors: Jiangbin Xia, Naruhiko Masaki, Monica Lira-cantu, Yukyeong Kim, Kejian Jiang, Shozo YanagidaAbstract:Poly(3,4-ethylenedioxythiophene) (PEDOT) is an excellent hole-conducting polymer able to replace the liquid I(-)/I3(-) Redox Electrolyte in dye-sensitized solar cells (DSCs). In this work we applied the in situ photoelectropolymerization technique to synthesize PEDOT and carried out a careful analysis of the effect of different doping anions on overall solar cell performance. The anions analyzed in this work are ClO4(-), CF3SO3(-), BF4(-), and TFSI(-). The best solar cell performance was observed when the TFSI(-) anion was used. Photoelectrochemical and impedance studies reveal that the doped anions in the PEDOT hole conductor system have great influences on I-V curves, conductivity, and impedance. The optimization of these parameters allowed us to obtain an iodine-free solid-state DSC with a maximum J(sc) of 5.3 mA/cm2, V(oc) of 750 mV, and a conversion efficiency of 2.85% which is the highest efficiency obtained so far for an iodine-free solid-state DSC using PEDOT as hole-transport material.
-
Fabrication of Quasi-solid-state Dye-sensitized TiO2 Solar Cells Using Low Molecular Weight Gelators.
Chemistry Letters, 1998Co-Authors: Wataru Kubo, Kei Murakoshi, Takayuki Kitamura, Wada Yuji, Kenji Hanabusa, Hirofusa Shirai, Shozo YanagidaAbstract:Low molecular weight gelators were applied to solidify the Redox Electrolyte in dye-sensitized TiO2 solar cells. The resulting quasi-solid-state dye-sensitized solar cells showed comparable efficiency and higher stability than the similar cell with the liquid phase Redox Electrolyte.