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.

Surface States Control Ultrafast Electron Injection in Dye/Semiconductor Colloidal Systems

Abstract: Electron injection from photoexcited dye molecules into semiconductor colloidal particles (TiO2 and ZrO2) is investigated by femtosecond (fs) spectroscopy. Ultrafast reaction dynamics in the dye/ZrO2-system with an inaccessible conduction band demonstrates efficient electron transfer to surface defect states.

Efficient special sensitisation of tio2 by surface derivatisation with transition metal cyanides

Abstract: Metallocyanide ions such as Fe II (CN) 4− 6 ,Ru II (CN) 4− 6 , Os II (CN) 4− 6 ,Re II (CN) 4− 6 , Mb IV (CN) 4− 8 and W IV (CN) 4− 8 form highly-coloured charge transfer complexes, by analogy with Prussian Blue, Fe 4 [Fe(CN) 6 ] 3 , on TiO 2 surfaces. When illuminated with light of photon energy less than the TiO 2 bandgap there is electron injection from the excited complex into the semiconductor conduction band. Photoelectrochemical systems in which TiO 2 electrodes and colloids are derivatised with these transition metal cyanide complexes are thereby sensitised to light in the visible part of the spectrum. Regenerative photoelectrochemical solar cell performance data are presented.

Bifunctional hole-shuttle molecule for improved interfacial energy level alignment and defect passivation in perovskite solar cells

Abstract: Abstract Perovskite solar cells have reached a power conversion efficiency over 25%, and the engineering of the interface between the perovskite and hole transport layer (HTL) has been crucial to achieve high performance. Here we design a bifunctional molecule CBz-PAI with carbazole-triphenylamine and phenylammonium iodide units to passivate defects at the perovskite/HTL interface. Owing to a favourable energy level alignment with the perovskite, the CBz-PAI acts as a hole shuttle between the perovskite layer and the HTL. This minimizes the difference between the quasi-Fermi level splitting of the perovskite, or ‘internal’ V oc , and the external device V oc , thus reducing voltage losses. As a result, solar cells incorporating CBz-PAI reach a stabilized power conversion efficiency of 24.7% and maintain 92.3% of the initial efficiency after 1,000 h under damp heat test (85 °C and 85% relative humidity) and 94.6% after 1,100 h under maximum power point-tracking conditions.

In-situ investigation of adsorption of dye and coadsorbates on TiO2 films using QCM-D, fluorescence and AFM techniques

Abstract: Simultaneous adsorption of dye molecules and coadsorbates is important for the fabrication of high-efficiency dyesensitized solar cells, but its mechanism is not well understood. Herein, we use a quartz crystal microbalance with dissipation technique (QCM-D) to study dynamically and quantitatively the sensitization of TiO2 in situ. We investigate dye loading for a ruthenium(II) polypyridyl complex (Z907), of a triphenylamine-based D-p-A dye (Y123), and of a ullazine sensitizer (JD21), as well as the simultaneous adsorption of the latter two with the coadsorbate chenodeoxycholic acid. By combining the QCM-D technique with fluorescence measurements, we quantify molar ratios between the dye and coadsorbate. Furthermore, we will present first studies using liquid-phase AFM on the adsorbed dye monolayer, thus obtaining complementary microscopic information that may lead to understanding of the adsorption mechanism on the molecular scale.

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.