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.

See-Through Dye-Sensitized Solar Cells: Photonic Reflectors for Tandem and Building Integrated Photovoltaics

Abstract: See-through dye-sensitized solar cells with 1D photonic crystal Bragg reflector photoanodes show an increase in peak external quantum efficiency of 47% while still maintaining high fill factors, resulting in an almost 40% increase in power conversion efficiency. These photoanodes are ideally suited for tandem and building integrated photovoltaics.

Sterically Hindered Phthalocyanines for Dye-Sensitized Solar Cells: Influence of the Distance between the Aromatic Core and the Anchoring Group

Abstract: A new phthalocyanine (Pc) bearing bulky peripheral substituents and a carboxylic anchoring group directly attached to the macrocycle has been prepared and used as a sensitizer in DSSCs, reaching 5.57% power conversion efficiency. In addition, an enhanced performance for the TT40 dye, previously reported by us, was achieved in optimized devices, obtaining a new record efficiency with Pc-sensitized cells.

Hole-conducting mediator for stable Sb2S3-sensitized photoelectrochemical solar cells

Abstract: Iodide redox (3I−/I3−), polysulfide redox (S2−/Sx2−), organic redox [TMTU/TMFDS2+: tetramethylthiourea/tetramethylformaminium-bis(trifluoromethanesulfonyl)imide], ferrocene redox (Fc/Fc+), nickel redox [Ni(II)/Ni(III)], and cobalt redox [Co(II)/Co(III)] hole conducting electrolytes were systematically investigated to determine their suitability for use in Sb2S3-sensitized photoelectrochemical solar cells. A long-term stability test and UV-visible spectral analyses revealed that Sb2S3-sensitized photoelectrochemical solar cells worked stably with Co(II)(o-phen)3(TFSI)2/Co(III)(o-phen)3(TFSI)3 [TFSI: bis(trifluoromethanesulfonyl)imide] as the redox mediator.

Silicon protected with atomic layer deposited TiO2: conducting versus tunnelling through TiO2

Abstract: The present work demonstrates that tuning the donor density of protective TiO2 layers on a photocathode has dramatic consequences for electronic conduction through TiO2 with implications for the stabilization of oxidation-sensitive catalysts on the surface. Vacuum annealing at 400 °C for 1 hour of atomic layer deposited TiO2 increased the donor density from an as-deposited value of 1.3 × 1019 cm−3 to 2.2 × 1020 cm−3 following the annealing step. Using an Fe(II)/Fe(III) redox couple it was shown that the lower dopant density only allows electron transfer through TiO2 under conditions of weak band bending. However it was shown that increasing the dopant density to 2.2 × 1020 cm−3 allows tunneling through the surface region of TiO2 to occur at significant band bending. An important implication of this result is that the less doped material is unsuitable for electron transfer across the TiO2/electrolyte interface if the potential is significantly more anodic than the TiO2 conduction band due to moderate to large band bending. This means that the lesser doped TiO2 can be used to prevent the inadvertent oxidation of sensitive species on the surface (e.g. H2 evolution catalysts) as long as the redox potential of the material is significantly more anodic than the TiO2 conduction band. Conversely, for situations where an oxidative process on the surface is desired, highly doped TiO2 may be used to enable current flow via tunneling.

I and i

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 …

Fast parallel algorithms for short-range molecular dynamics

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.

A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

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.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

Environmental Applications of Semiconductor Photocatalysis

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.