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.

Dyestuff, dye-sensitized solar cell, and method for manufacturing same

Abstract: PROBLEM TO BE SOLVED: To provide a sensitizing dyestuff for a solar cell which is also excellent in durability such as weather resistance, heat resistance and the like. SOLUTION: The dyestuff is shown by the general formula (1), ML 1 L 2 L 3 (1) wherein, M represents an element belonging to group 8 to group 10 of the long form of the periodic table, L 1 and L 2 individually represent a bidentate ligand shown by the general formula (2), and L 3 represents a bidentate ligand shown by the general formula (3). In the general formula (2), R 1 and R 2 individually represent a carboxy group or a group equivalent to the salt of the carboxy group. In the general formula (3), X represents a halogen atom and n is an integer of 0 to 2. COPYRIGHT: (C)2009,JPO&INPIT

PbZrTiO3 ferroelectric oxide as an electron extraction material for stable halide perovskite solar cells

Abstract: State-of-the-art halide perovskite solar cells employ semiconductor oxides as electron transport materials. Defects in these oxides, such as oxygen vacancies (Ovac), act as recombination centres and, in air and UV light, reduce the stability of the solar cell. Under the same conditions, the PbZrTiO3 ferroelectric oxide employs Ovac for the creation of defect-dipoles responsible for photo-carrier separation and current transport, evading device degradation. We report the application of PbZrTiO3 as the electron extraction material in triple cation halide perovskite solar cells. The application of a bias voltage (poling) up to 2 V, under UV light, is a critical step to induce charge transport in the ferroelectric oxide. Champion cells result in power conversion efficiencies of ∼11% after poling. Stability analysis, carried out at 1-sun AM 1.5 G, including UV light in air for unencapsulated devices, shows negligible degradation for hours. Our experiments indicate the effect of ferroelectricity, however alternative conducting mechanisms affected by the accumulation of charges or the migration of ions (or the combination of them) cannot be ruled out. Our results demonstrate, for the first time, the application of a ferroelectric oxide as an electron extraction material in efficient and stable PSCs. These findings are also a step forward in the development of next generation ferroelectric oxide-based electronic and optoelectronic devices.

Photochemical conversion and storage of solar energy

Abstract: Research activity in the area of photochemical conversion and storage of solar energy has grown enormously in recent years and currently involves interdisciplinary efforts from many areas such as photochemistry, electrochemistry, catalysis, solid state chemistry and photobiology. The coverage of this review is restricted to publications which appeared in the year 1983 and is discussed under several areas: H2, O2 production from water in homogeneous dye-based systems using redox catalysts, studies related to characterisation of catalysts and mechanism of their operation, heterogeneous photocatalysis and photodissociation of water using semiconductor dispersions and colloids, photogalvanic and photoelectrolysis-galvanic cells, dye-sensitization phenomena and other related topics. Photoelectrochemical studies with semiconductor electrodes (both for the conversion of visible light to electrical energy in regenerative cells and for direct photogeneration of useful chemicals) is one of the major areas in the photochemical solar energy conversion. The present coverage excludes a discussion of all such studies, except to provide a classified, annotated bibliography in the appendix. Fortunately, monitoring of the progress in the area of photochemical solar energy conversion is facilitated by the appearance of several review articles (Calvin, 1983a,b; Fox, 1983; Gratzel, 1983a; Harriman, 1983; Kutal, 1983; Gurevich and Pleskov, 1983; Zamarev and Parmon, 1983) and monographs (Claesson and Holmstrom, 1982; Gratzel, 1983b). There are numerous studies which can play a very important role in the eventual design of photochemical devices for the solar energy conversion which are again omitted in this coverage. These include studies on the improving of the efficiency of charge separation and the prevention of back reactions in photoredox quenching of molecular excited states-both by synthesis of novel sensitizers with appropriate tuning of ground, excited state properties and by the use of various organised assemblies such as micelles, vesicles, polymers, polyelectrolytes, microemulsions, monoand multilayer assemblies, and other multiphase systems such as cyclodextrins, clays, zeolites, etc. Similarly, mention should be made of various photobiological model systems for energy conversion: studies with isolated chloroplasts, chlorophyll or porphyrinquinone complexes, reaction center preparations, enzymes either as isolated ones or immobilised on various supports for water reduction and oxidation. There appears to be a very low level of activity on studies of photochemical energy storage via valence isomerisation (Childs et al., 1983; Jones et al., 1983: Olmsted et al., 1983; Philippopovlos et al., 1983). Porter has addressed the question of thermodynamic efficiency limits for a photochemical system that converts visible light into chemical potential (Porter, 1983).

Impact of the Synthesis Route on the Water Oxidation Kinetics of Hematite Photoanodes

Abstract: Operando spectroelectrochemical analysis is used to determine the water oxidation reaction kinetics for hematite photoanodes prepared using four different synthetic procedures. While these photoano...

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.