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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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TL;DR: In this article, the authors discuss recent research on junctions made up of a network of nanometer-sized oxide particles such as zinc oxide, tungsten trioxide niobium oxide and titanium dioxide, which are interconnected to allow for electronic conduction to take place.

17 citations

Journal ArticleDOI
TL;DR: In this article, a charged cyclometalated iridium(III) complexes with non-p-electron-conjugated ancillary chelates were synthesized and their electrochemical and photophysical properties studied.
Abstract: New charged cyclometalated iridium(III) complexes [Ir(ppy)2(L)](PF6) [ppy = 2-phenylpyridine; L = bis(pyrazol-1-yl)methane (for 1); L = bis(3,5-dimethylpyrazol-1-yl)methane (for 2)] were synthesized and their electrochemical and photophysical properties studied. These complexes with non-p-electron-conjugated ancillary chelates exhibit significantly blueshifted emission relative to those of commonly used derivatives with NN ancillary ligands such as bipyridine or phenanthroline. Both X-ray and theoretical analysis based on time-dependent density functional theory (TD-DFT) reveal that the binding of Ir to the bis(pyrazol-1-yl)methane ancillary ligand is much weaker than that to the phenylpyridine main ligand; the effect is enhanced in the excited state. As a result, the ancillary ligand does not participate in low-energy excitations and triplet emission, and the electronic transitions are concentrated on the main chromophoric ligands. The blueshift feature is attributed to emission originating from the main cyclometalated ligands, in contrast to emitters with the NN chromophoric ancillary ligand. In addition, complex 2 exhibits a one order of magnitude higher non-radiative decay rate than complex 1, which is attributed to the steric hindrance of the methyl groups that leads to a more loosely bound ancillary ligand.

17 citations

Journal ArticleDOI
TL;DR: In this paper, the electrical conductivity of nanocrystalline anatase titanium dioxide powders was measured using the powder-solution-composite (PSC) method.
Abstract: Nanocrystalline anatase titanium dioxide powders were produced by a hydrothermal synthesis route in pure form and substituted with trivalent Ga3+ and Y3+ or pentavalent Nb5+ with the intention of creating acceptor or donor states, respectively. The electrical conductivity of each powder was measured using the powder-solution-composite (PSC) method. The conductivity increased with the addition of Nb5+ from 3 similar to x similar to 10-3 similar to S/cm to 10 similar to x similar to 10-3 similar to S/cm in as-prepared powders, and from 0.3 similar to x similar to 10-3 similar to S/cm to 0.9 similar to x similar to 10-3 similar to S/cm in heat-treated powders (520 degrees C, 1 similar to h). In contrast, substitution with Ga3+ and Y3+ had no measureable effect on the material's conductivity. The lack of change with the addition of Ga3+ and Y3+, and relatively small increase upon Nb5+ addition is attributed to ionic compensation owing to the highly oxidizing nature of hydrothermal synthesis.

17 citations

Journal ArticleDOI
TL;DR: A series of six new subphthalocyanines bearing an ethynylcarboxyphenyl anchoring unit and decorated with a variety of substituents at the peripheral position of the macrocycle have been synthesized in order to investigate the effect of the peripheral substituent on the performance of dye-sensitized solar cells.
Abstract: A series of six new subphthalocyanines (SubPcs) bearing an ethynylcarboxyphenyl anchoring unit and decorated with a variety of substituents at the peripheral position of the macrocycle have been synthesized in order to investigate the effect of the peripheral substituent on the performance of dye-sensitized solar cells.

17 citations


Cited by
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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