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Michael Grätzel

Bio: Michael Grätzel is an academic researcher from École Polytechnique Fédérale de Lausanne. The author has contributed to research in topics: Dye-sensitized solar cell & Perovskite (structure). The author has an hindex of 248, co-authored 1423 publications receiving 303599 citations. Previous affiliations of Michael Grätzel include University of California, Berkeley & Siemens Energy Sector.


Papers
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Book ChapterDOI
01 Jan 1988
TL;DR: In this article, the energy conversion efficiency of photoelectrochemical solar cells using those oxide semiconductor electrodes which are stable in contact with aqueous electrolytes is low because their wide band gaps do not permit a photoresponse to the visible spectrum.
Abstract: The energy conversion efficiency of photoelectrochemical solar cells using those oxide semiconductor electrodes which are stable in contact with aqueous electrolytes is low because their wide band gaps do not permit a photoresponse to the visible spectrum. By adsorption of a sufficient quantity of a charge-transfer dye with intimate contact to the semiconductor, the electrode can be sensitised to visible radiation. Titanium dioxide electrodes were derivatised by attached ruthenium bis- and tris- bipyridyl and zinc porphyrin dyes and their efficiency as photoelectrochemical solar cell electrodes is reported.

5 citations

01 Jan 1993
TL;DR: In this paper, the performance of bis(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) type redox sensitizers was investigated.
Abstract: cis-X~Bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) complexes (X = C1-, Br, I-, CN-, and SCN-) were prepared and characterized with respct to their absorption, luminescence, and redox behavior. They act as efficient charge-transfer sensitizers for nanocrystalline Ti02 films (thickness 8-1 2 pm) of very high internal surface area (roughness factor ca. lOOO), prepared by sintering of 15-30-nm colloidal titania particles on a conducting glass support. The performance of cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) (1) was found to be outstanding and is unmatched by any other known sensitizer. Nanocrystalline Ti02 films coated with a monolayer of 1 harvest visible light very efficiently, their absorption threshold being around 800 nm. Conversion of incident photons into electric current is nearly quantitative over a large spectral range. These films were incorporated in a thin-layer regenerative solar cell equipped with a light-reflecting counter electrode. Short-circuit photocurrents exceeding 17 mA/cmZ were obtained in simulated AM 1.5 sunlight using lithium iodide/triiodide in acetonitrile or acetonitrile/ 3-methyl-2-oxazolidinone mixtures as redox electrolyte. The open-circuit photovoltage was 0.38 V and increased to 0.72 V by treating the dye-covered film with 4-terr-butylpyridine. A solar-to-electric energy conversion efficiency of 10% was attained with this system. The effect of temperature on the power output and long-term stability of the dye was also investigated. For the first time, a device based on a simple molecular light absorber attains a conversion efficiency commensurate with that of conventional silicon-based photovoltaic cells. a broad spectral range in the~isible.~ A subsequent time-resolved luminescence study by Eichberger and Willig3m showed this effect to be due to ultrafast (7 < 7 ps) electron injection from the excited state of the complex into the conduction band of the oxide occurring with a quantum yield near 100%. These important observations warrant further studies of the behavior of the relatively unexplored class of bis(2,2'-bipyridyl)ruthenium(II)- type redox sensitizers. Apart from their chemical stability and ease of interfacial charge exchange with semiconducting solids, the attractive feature of these complexes is their large visible light harvesting capacity which is superior to that of the widely studied tris(bipyridy1) Ru(I1) analogues, making them a judicious choice for solar energy conversion devices.

5 citations

Journal ArticleDOI
TL;DR: In this paper , the rate-determining step (RDS) of OER on NiFe LDH based electrocatalysts is from O to *OOH in neutral electrolytes, while *OH formation is the RDS in neutral conditions.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the electron transfer kinetics in dye-sensitized TiO2 films used in commercial photovoltaic devices were studied and the electron injection in these dye sensitized films occurs on an ultrafast time scale with two components, 150 fs and 1·2 ps.
Abstract: Sub-picosecond transient absorption study has been employed to study the electron transfer kinetics in the dye-sensitized TiO2 films used in commercial photovoltaic devices. The electron injection in these dye sensitized films occurs on an ultrafast time scale with two components, 150 fs and 1·2 ps.

5 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

29,323 citations

Journal ArticleDOI
24 Oct 1991-Nature
TL;DR: In this article, the authors describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency.
Abstract: THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods1. Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm-2) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.

26,457 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: The slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses as discussed by the authors, which is a serious problem.
Abstract: The civilian, commercial, and defense sectors of most advanced industrialized nations are faced with a tremendous set of environmental problems related to the remediation of hazardous wastes, contaminated groundwaters, and the control of toxic air contaminants. For example, the slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses. Over the last 10 years problems related to hazardous waste remediation have emerged as a high national and international priority.

17,188 citations