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Arthur J. Nozik - One of the best experts on this subject based on the ideXlab platform.

  • Introduction to Solar Photon Conversion
    Chemical Reviews, 2010
    Co-Authors: Arthur J. Nozik, John H. Miller
    Abstract:

    The efficient and cost-effective direct Conversion of solar Photons into solar electricity and solar fuels is one of the most important scientific and technological challenges of this century. It is estimated that at least 20 terawatts of carbon-free energy (1 and 1/2 times the total amount of all forms of energy consumed today globally), in the form of electricity and liquid and gaseous fuels, will be required by 2050 in order to avoid the most serious consequences of global climate change and to ensure adequate global energy supply that will avoid economic chaos. But in order for solar energy to contribute a major fraction of future carbon-free energy supplies, it must be priced competitively with, or perhaps even be less costly than, energy from fossil fuels and nuclear power as well as other renewable energy resources. The challenge of delivering very low-cost solar fuels and electricity will require groundbreaking advances in both fundamental and applied science. This Thematic Issue on Solar Photon Conversion will provide a review by leading researchers on the present status and prognosis of the science and technology of direct solar photoConversion to electricity and fuels. The topics covered include advanced and novel concepts for low-cost photovoltaicmore » (PV) energy based on chemistry (dye-sensitized photoelectrodes, organic and molecular PV, multiple exciton generation in quantum dots, singlet fission), solar water splitting, redox catalysis for water oxidation and reduction, the role of nanoscience and nanocrystals in solar photoConversion, photoelectrochemical energy Conversion, and photoinduced electron transfer. The direct Conversion of solar Photons to electricity via photovoltaic (PV) cells is a vital present-day commercial industry, with PV module production growing at about 75%/year over the past 3 years. However, the total installed yearly averaged energy capacity at the end of 2009 was about 7 GW-year (0.2% of global electricity usage). Thus, there is potential for the PV industry to grow enormously in the future (by factors of 100-300) in order for it to provide a significant fraction of total global electricity needs (currently about 3.5 TW). Such growth will be greatly facilitated by, and probably even require, major advances in the Conversion efficiency and cost reduction for PV cells and modules; such advances will depend upon advances in PV science and technology, and these approaches are discussed in this Thematic Issue. Industrial and domestic electricity utilization accounts for only about 30% of the total energy consumed globally. Most ({approx}70%) of our energy consumption is in the form of liquid and gaseous fuels. Presently, solar-derived fuels are produced from biomass (labeled as biofuels) and are generated through biological photosynthesis. The global production of liquid biofuels in 2009 was about 1.6 million barrels/day, equivalent to a yearly output of about 2.5 EJ (about 1.3% of global liquid fuel utilization). The direct Conversion of solar Photons to fuels produces high-energy chemical products that are labeled as solar fuels; these can be produced through nonbiological approaches, generally called artificial photosynthesis. The feedstocks for artificial photosynthesis are H{sub 2}O and CO{sub 2}, either reacting as coupled oxidation-reduction reactions, as in biological photosynthesis, or by first splitting H{sub 2}O into H{sub 2} and O{sub 2} and then reacting the solar H{sub 2} with CO{sub 2} (or CO produced from CO2) in a second step to produce fuels through various well-known chemical routes involving syngas, water gas shift, and alcohol synthesis; in some applications, the generated solar H{sub 2} itself can be used as an excellent gaseous fuel, for example, in fuel cells. But at the present time, there is no solar fuels industry. Much research and development are required to create a solar fuels industry, and this Thematic Issue presents several reviews on the relevant solar fuels science and technology. The first three manuscripts relate to the daunting problem of producing solar fuels. Lewis and colleagues present a comprehensive review of solar water splitting based on semiconductor electrodes. The semiconductor electrodes are either in direct contact with an aqueous electrolyte, creating a semiconductor-liquid junction, in which case this defines a true photoelectrochemical (PEC) configuration, or the semiconductors can form buried p-n junctions connected to metal anodes and/or cathodes, in which case various combination of PV and PEC cell configurations are possible. The issues of cell energetics, cell efficiency, photocorrosion, and electrocatalysis are discussed in detail. Nocera et al. first discuss the global energy problem and review the issues and technologies for solar energy storage. Then they focus on solar fuels as the best option for solar energy storage at sufficient scale to solve the looming energy crisis.« less

  • nanostructured and photoelectrochemical systems for solar Photon Conversion
    2008
    Co-Authors: Mary D. Archer, Arthur J. Nozik
    Abstract:

    Introduction (A J Nozik & M D Archer) Semiconductor Photoelectrochemistry (R Memming & R J D Miller) Non-Dye-Sensitised Regenerative Solar Cells (N S Lewis & P V Kamat) Dye-Sensitised Regenerative Solar Cells (M Gratzel & S-E Lindquist) Photoelectrochemical Storage Cells (G Hodes & S Licht) Photoinduced Electron Transfer in Molecular Donor-Acceptor Assemblies (J Miller et al.) Photoinduced Electron Transfer in Microheterogeneous Systems (K Kalyanasundaram & J-E Moser) Quantum Well and Quantum Dot Devices (A J Nozik) Hydrogen Production and Water Splitting (J A Turner & M Anpo) Carbon Dioxide Fixation (E Fujita & D L DuBois) Dark and Photoassisted Nitrogen Fixation (J L Dzi Gielewski) Photoreduction on Nitrogen on Titania in Gas-Phase Systems (G N Schrauzer) Photochemical Molecular Energy Storage (M D Archer) Solar Photochemical Synthesis of Useful Chemicals (M D Archer) Solar Photochemical Remediation of Air and Water (N Serpone & E Pelizzetti) Experimental Techniques for Characterisation of Photoelectrochemical Systems (L M Peter & H Tributsch) Electron Transfer Dynamics at Semiconductor/Liquid Interfaces (F Willig) Novel Materials for Photochemical and Photoelectrochemical Systems (R Tenne & J J Kelly).

  • Nanostructured and Photoelectrochemical Systems for Solar Photon Conversion - Nanostructured And Photoelectrochemical Systems For Solar Photon Conversion
    Series on Photoconversion of Solar Energy, 2008
    Co-Authors: Mary D. Archer, Arthur J. Nozik
    Abstract:

    Introduction (A J Nozik & M D Archer) Semiconductor Photoelectrochemistry (R Memming & R J D Miller) Non-Dye-Sensitised Regenerative Solar Cells (N S Lewis & P V Kamat) Dye-Sensitised Regenerative Solar Cells (M Gratzel & S-E Lindquist) Photoelectrochemical Storage Cells (G Hodes & S Licht) Photoinduced Electron Transfer in Molecular Donor-Acceptor Assemblies (J Miller et al.) Photoinduced Electron Transfer in Microheterogeneous Systems (K Kalyanasundaram & J-E Moser) Quantum Well and Quantum Dot Devices (A J Nozik) Hydrogen Production and Water Splitting (J A Turner & M Anpo) Carbon Dioxide Fixation (E Fujita & D L DuBois) Dark and Photoassisted Nitrogen Fixation (J L Dzi Gielewski) Photoreduction on Nitrogen on Titania in Gas-Phase Systems (G N Schrauzer) Photochemical Molecular Energy Storage (M D Archer) Solar Photochemical Synthesis of Useful Chemicals (M D Archer) Solar Photochemical Remediation of Air and Water (N Serpone & E Pelizzetti) Experimental Techniques for Characterisation of Photoelectrochemical Systems (L M Peter & H Tributsch) Electron Transfer Dynamics at Semiconductor/Liquid Interfaces (F Willig) Novel Materials for Photochemical and Photoelectrochemical Systems (R Tenne & J J Kelly).

  • Exciton Multiplication and Relaxation Dynamics in Quantum Dots: Applications to Ultra-High Efficiency Solar Photon Conversion
    2006 IEEE 4th World Conference on Photovoltaic Energy Conference, 2006
    Co-Authors: Arthur J. Nozik
    Abstract:

    We show how semiconductor quantum dots may greatly increase Photon Conversion efficiencies by producing multiple excitons from a single Photon. This is possible because quantization of energy levels in quantum dots enhances Auger processes, eliminates the requirement to conserve crystal momentum, and thus promotes multiple exciton generation, Quantum yields of 300% for exciton formation in PbSe, PbS, and PbTe quantum dots have been reported at Photon energies about 4 times the HOMO-LUMO transition energy (QD bandgap), indicating the formation of 3 excitons/Photon for all photoexcited quantum dots.

  • exciton multiplication and relaxation dynamics in quantum dots applications to ultrahigh efficiency solar Photon Conversion
    Inorganic Chemistry, 2005
    Co-Authors: Arthur J. Nozik
    Abstract:

    Huge amounts of carbon-free energy will be required during the coming decades in order to stabilize atmospheric CO 2 to acceptable levels. Solar energy is the largest source of non-carbonaceous energy and can be used to produce both electricity and fuel. However, the ratio of the areal cost to the Conversion efficiency for devices converting solar Photons to electricity or fuel must be reduced by at least 1 order of magnitude from the present values; this requires large increases in the cell efficiency and large reductions in the cost per unit area. We have shown how semiconductor quantum dots may greatly increase Photon Conversion efficiencies by producing multiple excitons from a single Photon. This is possible because quantization of energy levels in quantum dots slows the cooling of hot excitons, promotes multiple exciton generation, and lowers the Photon energy threshold for this process. Quantum yields of 300% for exciton formation in PbSe quantum dots have been reported at Photon energies 3.8 times the HOMO-LUMO transition energy, indicating the formation of three excitons/Photon for all photoexcited quantum dots. Similar high quantum yields have also been reported for PbS quantum dots. A new model for this effect that is based on a coherent superposition of multiple excitonic states has been proposed.

A. Slaoui - One of the best experts on this subject based on the ideXlab platform.

  • Photon Conversion in Tb,Yb:CaxSr1-xAl2O4 nanocrystals
    Journal of Luminescence, 2018
    Co-Authors: Thomas Fix, Hervé Rinnert, Jean-luc Rehspringer, A. Slaoui
    Abstract:

    Abstract In this work the fabrication and the photoluminescence properties of CaxSr1-xAl2O4 nanocrystals doped with Ca, Tb and Yb are investigated. The photoluminescence quantum yield measured at 980 nm of the Yb doped CaxSr1-xAl2O4 nanocrystals is found to be 8% for an excitation in the ultraviolet range. However the quantum efficiency decreases with the insertion of Tb. Photoluminescence excitation experiments and time-resolved photoluminescence both conclusively demonstrate that no energy transfer between Tb and Yb occurs in this host matrix.

  • Functionalization of a polymer encapsulant with Photon Conversion
    Solar Energy Materials and Solar Cells, 2015
    Co-Authors: T. Fix, Hervé Rinnert, J. -l. Rehspringer, A. Slaoui
    Abstract:

    Current silicon solar cell modules use a polymer encapsulant to protect the solar cells. This polymer is essential but it has a passive action. In this work, we propose to functionalize the polymer by inserting inorganic nanoparticles in it so that it converts ultraviolet Photons into infrared Photons. The final goal is to increase the overall efficiency of the silicon solar modules. The polymer proposed is ethylene vinyl acetate which is a commonly used encapsulant, to which Nd, or Yb, or Tb-Yb doped CeO2 nanoparticles are added for the Photon Conversion. Although no improvement in efficiency was observed in solar cells including the nanoparticles in the encapsulant, the present work paves the way for the integration of Photon downConversion into modules without the use of vacuum deposition technologies.

A. H. Kung - One of the best experts on this subject based on the ideXlab platform.

Safavi-naeini, Amir H. - One of the best experts on this subject based on the ideXlab platform.

  • A silicon-organic hybrid platform for quantum microwave-to-optical transduction
    'IOP Publishing', 2020
    Co-Authors: Witmer, Jeremy D., Mckenna, Timothy P., Arrangoiz-arriola Patricio, Van Laer Raphaël, Lin Francis, Luo Jingdong, Alex Wollack E., Jen, Alex K-y, Safavi-naeini, Amir H.
    Abstract:

    Low-loss fiber optic links have the potential to connect superconducting quantum processors together over long distances to form large scale quantum networks. A key component of these future networks is a quantum transducer that coherently and bidirectionally converts Photons from microwave frequencies to optical frequencies. We present a platform for electro-optic Photon Conversion based on silicon-organic hybrid Photonics. Our device combines high quality factor microwave and optical resonators with an electro-optic polymer cladding to perform microwave-to-optical Photon Conversion from 6.7 GHz to 193 THz (1558 nm). The device achieves an electro-optic coupling rate of 590 Hz in a millikelvin dilution refrigerator environment. We use an optical heterodyne measurement technique to demonstrate the single-sideband nature of the Conversion with a selectivity of approximately 10 dB. We analyze the effects of stray light in our device and suggest ways in which this can be mitigated. Finally, we present initial results on high-impedance spiral resonators designed to increase the electro-optic coupling

  • A silicon-organic hybrid platform for quantum microwave-to-optical transduction
    2019
    Co-Authors: Witmer, Jeremy D., Mckenna, Timothy P., Arrangoiz-arriola Patricio, Van Laer Raphaël, Wollack E. Alex, Lin Francis, Jen, Alex K. -y., Luo Jingdong, Safavi-naeini, Amir H.
    Abstract:

    Low-loss fiber optic links have the potential to connect superconducting quantum processors together over long distances to form large scale quantum networks. A key component of these future networks is a quantum transducer that coherently and bidirectionally converts Photons from microwave frequencies to optical frequencies. We present a platform for electro-optic Photon Conversion based on silicon-organic hybrid Photonics. Our device combines high quality factor microwave and optical resonators with an electro-optic polymer cladding to perform microwave-to-optical Photon Conversion from 6.7 GHz to 193 THz (1558 nm). The device achieves an electro-optic coupling rate of 330 Hz in a millikelvin dilution refrigerator environment. We use an optical heterodyne measurement technique to demonstrate the single-sideband nature of the Conversion with a selectivity of approximately 10 dB. We analyze the effects of stray light in our device and suggest ways in which this can be mitigated. Finally, we present initial results on high-impedance spiral resonators designed to increase the electro-optic coupling.Comment: 31 pages, 13 figure

Kazuyoshi Itoh - One of the best experts on this subject based on the ideXlab platform.

  • Selective labeling of a single organelle by using two-Photon Conversion of a photoconvertible fluorescent protein
    Multiphoton Microscopy in the Biomedical Sciences VIII, 2008
    Co-Authors: Wataru Watanabe, Tomoko Shimada, Sachihiro Matsunaga, Daisuke Kurihara, Kiichi Fukui, Nobuhiro Tsutsumi, Shin-ichi Arimura, Kazuyoshi Itoh
    Abstract:

    We present space-selective labeling of organelles by using two-Photon Conversion of a photoconvertible fluorescent protein with near-infrared femtosecond laser pulses. Two-Photon excitation of photoconvertible fluorescent-protein, Kaede, enables space-selective labeling of organelles. We alter the fluorescence of target mitochondria in a tobacco BY-2 cell from green to red by focusing femtosecond laser pulses with a wavelength of 750 nm.

  • Single-organelle tracking by two-Photon Conversion.
    Optics Express, 2007
    Co-Authors: Wataru Watanabe, Tomoko Shimada, Sachihiro Matsunaga, Daisuke Kurihara, Kiichi Fukui, Shin-ichi Shin-ichi Arimura, Nobuhiro Tsutsumi, Keisuke Isobe, Kazuyoshi Itoh
    Abstract:

    Spatial and temporal information about intracellular objects and their dynamics within a living cell are essential for dynamic analysis of such objects in cell biology. A specific intracellular object can be discriminated by photoactivatable fluorescent proteins that exhibit pronounced light-induced spectral changes. Here, we report on selective labeling and tracking of a single organelle by using two-Photon Conversion of a photoconvertible fluorescent protein with near-infrared femtosecond laser pulses. We performed selective labeling of a single mitochondrion in a living tobacco BY-2 cell using two-Photon photoConversion of Kaede. Using this technique, we demonstrated that, in plants, the directed movement of individual mitochondria along the cytoskeletons was mediated by actin filaments, whereas microtubules were not required for the movement of mitochondria. This single-organelle labeling technique enabled us to track the dynamics of a single organelle, revealing the mechanisms involved in organelle dynamics. The technique has potential application in direct tracking of selective cellular and intracellular structures.