Author
Michael Grätzel
Other affiliations: University of California, Berkeley, Siemens Energy Sector, University of Bath ...read more
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 published on a yearly basis
Papers
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TL;DR: In this paper, anionic hydrotalcite is utilized as a gelator to assist the formation of gel electrolyte in dye-sensitized solar cells (DSSCs), for its capability to resolve the leakage issue of liquid electrolyte.
Abstract: In recent research in clean energy applications, clay has gained significant interest, especially as a gelator in dye-sensitized solar cells (DSSCs), for its capability to resolve the leakage issue of liquid electrolyte. In this paper, anionic hydrotalcite is utilized as a gelator to assist the formation of gel electrolyte in DSSCs. Three types of hydrotalcite with exchangeable anions, viz. NO3− (CL-N), CO32− (CL-C) and SO42− (CL-S), were synthesized with similar morphologies via the co-precipitation method. It is observed that the gel formation of hydrotalcite strongly depends on the exchangeable anions present in the hydrotalcite. The objective of this work is to understand the effect of hydrotalcite anions on the photovoltage and the photocurrent in the gel electrolyte through electrochemical analysis. With increasing ion affinity, the Voc increases. This is attributed to Li+ intercalation with hydrotalcite compound resulting in the elevation of the conduction band of TiO2. With increasing ion affinity, the Jsc decreases. This is attributed to the decreasing diffusion coefficient of triiodide and the increasing difficulty in the injection process. For anions with low ion affinity in hydrotalcite, the diffusion of the redox couple is not significantly affected by the high viscosity of the gel. Furthermore, the study indicates that proper selection of hydrotalcite compounds not only produces a quasi-solid gel electrolyte, but also increases the efficiency of the solar cells: the device performance was improved from 7.8% (liquid electrolyte) to 8.4% (hydrotalcite gel electrolyte).
28 citations
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TL;DR: This work demonstrates the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties and highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovSkite structures.
Abstract: Here, we demonstrate the incorporation of monovalent cation additives into CH3NH3PbI3 perovskite in order to adjust the optical, excitonic, and electrical properties. The possibility of doping was investigated by adding monovalent cation halides with similar ionic radii to Pb2+, including Cu+, Na+, and Ag+. A shift in the Fermi level and a remarkable decrease of sub-bandgap optical absorption, along with a lower energetic disorder in the perovskite, was achieved. An order-of-magnitude enhancement in the bulk hole mobility and a significant reduction of transport activation energy within an additive-based perovskite device was attained. The confluence of the aforementioned improved properties in the presence of these cations led to an enhancement in the photovoltaic parameters of the perovskite solar cell. An increase of 70 mV in open circuit voltage for AgI and a 2 mA/cm2 improvement in photocurrent density for NaI- and CuBr-based solar cells were achieved compared to the pristine device. Our work paves the way for further improvements in the optoelectronic quality of CH3NH3PbI3 perovskite and subsequent devices. It highlights a new avenue for investigations on the role of dopant impurities in crystallization and controls the electronic defect density in perovskite structures.
28 citations
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TL;DR: In this paper, it was shown that surface-bound peroxo titanium complexes are formed during photolytic water cleavage in closed systems and as aresult of oxygen photo-uptake.
Abstract: By using the redox indicators o-dianisidine and o-toluidine as regents for quantitative analysis, it is shown that in colloidal TiO2–Pt dispersions surface-bound peroxo titanium complexes are formed during photolytic water cleavage in closed systems and as aresult of oxygen photo-uptake.
27 citations
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TL;DR: Titanium dioxide (anatase, rutile) and quasi-amorphous tin dioxide are prepared on F-doped SnO2 in the form of dense thin films, which can serve as electron-selective layers in perovskite solar cel...
Abstract: Titanium dioxide (anatase, rutile) and quasi-amorphous tin dioxide are prepared on F-doped SnO2 in the form of dense thin films, which can serve as electron-selective layers in perovskite solar cel...
27 citations
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TL;DR: The activity of TiO2 particles for photocatalytic oxygen evolution in the presence of Ag+ ions as an electron acceptor is increased 10 times by the removal of surface hydroxy groups through thermal treatment.
Abstract: The activity of TiO2 particles for photocatalytic oxygen evolution in the presence of Ag+ ions as an electron acceptor is increased 10 times by the removal of surface hydroxy groups through thermal treatment.
27 citations
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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
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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
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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