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Michael Graetzel

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Publications associées (1 223)

Efficient orange light-emitting electrochemical cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Rosario Scopelliti

We report the first bis-cyclometalated cationic iridium(III) complex with N-aryl-substituted 1H-imidazo [4,5-f][1,10]phenanthroline. The complex emits yellow-orange phosphorescence with a maximum at 583 nm, a quantum yield of 43%, and an excited-state life ...

Royal Society of Chemistry2012

Effect of Posttreatment of Titania Mesoscopic Films by TiCl4 in Solid- State Dye-Sensitized Solar Cells: A Time-Resolved Spectroscopy Study

Michael Graetzel, Jacques-Edouard Moser, Arianna Marchioro, Angela Punzi, Amalie Dualeh

Post-treatment of mesoporous titanium dioxide films by TiCl4 solutions is commonly applied during the fabrication of solid-state dye-sensitized solar cells (ssDSCs), as this operation markedly improves the performance of the photovoltaic device. The effect ...

Amer Chemical Soc2012

Convergent Synthesis of Near-Infrared Absorbing, "Push-Pull", Bisthiophene-Substituted, Zinc(II) Phthalocyanines and their Application in Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Jun Ho Yum

Zinc(II) phthalocyanine dyes that contain triarylamine-terminated bisthiophene and hexylbisthiophene groups have been synthesized by a convergent approach by using carboxytriiodoZnPc as a precursor. Further transformation of the iodo groups by a Pd-catalyz ...

2012

Economical Pt-Free Catalysts for Counter Electrodes of Dye-Sensitized Solar Cells

Michael Graetzel, Ulf Anders Hagfeldt, Liang Wang

Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr3C2, CrN, VC(N), VN ...

2012

Great expectations for photoelectrochemical water splitting

Michael Graetzel, Stanley David Tilley

The first Bilateral Energy Conference-organized jointly by the E-MRS and MRS-was held at the E-MRS Spring Meeting this year and included the first symposium to appear in Europe dedicated to solar hydrogen production. The strong turnout and high level of in ...

Elsevier Science Bv2012

The Transient Photocurrent and Photovoltage Behavior of a Hematite Photoanode under Working Conditions and the Influence of Surface Treatments

Michael Graetzel, Kevin Sivula, Florian Le Formal

Hematite (alpha-Fe2O3) is widely recognized as a promising candidate for the production of solar fuels via water splitting, but its intrinsic optoelectronic properties have limited its performance to date. In particular, the large electrochemical overpoten ...

American Chemical Society2012

A new generation of platinum and iodine free efficient dye-sensitized solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Takeru Bessho, Chenyi Yi, Julien Edouard Frey

We report a series of cobalt complexes with various polypyridyl ligands, where the oxidation potential is tuned from 0.17 to 0.34 V vs. ferrocene. The highest occupied molecular orbitals (HOMO) of the cobalt complexes were stabilized by adding electron acc ...

2012

Avoiding Diffusion Limitations in Cobalt(III/II)-Tris(2,2'-Bipyridine)-Based Dye-Sensitized Solar Cells by Tuning the Mesoporous TiO2 Film Properties

Pascal Comte, Michael Graetzel, Chenyi Yi, Hoi Nok Tsao

Dye-sensitized solar cells based on electrolytes containing cobalt complexes as redox shuttles typically suffer a major limitation in terms of slow diffusion of those couples through the mesoporous TiO2 film. This results in a drop of the photocurrent dens ...

Wiley-Blackwell2012

Phosphorescent cationic iridium(III) complexes with cyclometalating 1H-indazole and 2H-[1,2,3]-triazole ligands

Michael Graetzel, Mohammad Khaja Nazeeruddin, Rosario Scopelliti

Two new cationic iridium(III) complexes with cyclometalating 1-phenylindazole or 2-phenyl-1,2,3-triazole ligands, (C boolean AND N)(2)Ir(4,4'-di-tert-butyl-2,2'-dipyridyl), exhibit yellow or green phosphorescence with quantum yields and excited stat ...

Elsevier2012

A Ga2O3 underlayer as an isomorphic template for ultrathin hematite films toward efficient photoelectrochemical water splitting

Michael Graetzel, Maurin Cornuz, Kevin Sivula, Florian Le Formal, Jérémie Minh-Châu Brillet, Nicolas Tétreault, Takashi Hisatomi

Hematite photoanodes for photoelectrochemical (PEC) water splitting are often fabricated as extremely-thin films to minimize charge recombination because of the short diffusion lengths of photoexcited carriers. However, poor crystallinity caused by structu ...

2012

Light Energy Conversion by Mesoscopic PbS Quantum Dots/TiO2 Heterojunction Solar Cells

Michael Graetzel, Lioz Etgar, Thomas Moehl

Solid state PbS quantum dots (QDs)/TiO2 heterojunction solar cells were produced by depositing PbS QDs on a 500 nm thick mesoscopic TiO2 films using layer-by-layer deposition. Importantly, the PbS QDs act here as photosensitizers and at the same time as ho ...

American Chemical Society2012

Dynamics of photogenerated holes in surface modified alpha-Fe2O3 photoanodes for solar water splitting

Michael Graetzel, Kevin Sivula, Takashi Hisatomi

This paper addresses the origin of the decrease in the external electrical bias required for water photoelectrolysis with hematite photoanodes, observed following surface treatments of such electrodes. We consider two alternative surface modifications: a c ...

National Academy of Sciences2012

Blue Phosphorescence of Trifluoromethyl- and Trifluoromethoxy-Substituted Cationic Iridium(III) Isocyanide Complexes

Michael Graetzel, Mohammad Khaja Nazeeruddin, Rosario Scopelliti

We report the first comprehensive comparative synthetic, structural, electrochemical, and spectroscopic study of an extended series of fluorocarbon-modified iridium(III) complexes. We prepared seven new cationic Ir(III) complexes with tert-butyl isocyanide ...

American Chemical Society2012

Click-Functionalized Ru(II) Complexes for Dye-Sensitized Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Paul Joseph Dyson, Nuttapol Pootrakulchote, Ryan Dykeman, Amaresh Mishra

Three heteroleptic ruthenium complexes incorporating new ancillary ligands synthesized by sequential connection of different alkyl functionalities with triazole as a linker are prepared using click chemistry. These sensitizers exhibit low-energy metal-to-l ...

Wiley-VCH Verlag Berlin2012

A structural study of DPP-based sensitizers for DSC applications

Michael Graetzel, Mohammad Khaja Nazeeruddin, Davide Di Censo, Jun Ho Yum, Magdalena Anna Marszalek, Peng Gao, Thomas Wesley Holcombe, Junghyun Yoon, Kasparas Rakstys

Four D-pi-A sensitizers comprising a thienyl-diketopyrrolopyrrole (ThDPP) bridge were synthesized and tested in iodide/triiodide liquid electrolyte DSC devices. The dye series was strategically designed to develop a structure-property relationship. The bes ...

Royal Society of Chemistry2012

Reducing recombination in ZnO photoanodes for dye sensitised solar cells through simple chemical synthesis

Michael Graetzel, Vincent Laporte, Lioz Etgar

A method has been developed to synthesise zinc oxide nanowire arrays that demonstrate superior device performance compared to conventional ZnO nanowires within dye sensitised solar cells (DSSCs). This simple yet effective methodology has produced nanowires ...

Royal Society of Chemistry2012

Conduction Through Viscoelastic Phase in a Redox-Active Ionic Liquid at Reduced Temperatures

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Jan Cornelius Brauer, Verner Thorsmolle

The phase diagram of the redox active ionic liquid 1-methyl-3-propylimidazolium iodide (PMII) is examined as a function of temperature and iodine concentration. Beyond a threshold concentration of 3.9 M, the formation of higher polyiodides gives rise to a ...

Wiley2012

Fine-tuning the Electronic Structure of Organic Dyes for Dye-Sensitized Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Hoi Nok Tsao, Peng Gao

A series of metal-free organic dyes exploiting different combinations of (hetero)cyclic linkers (benzene, thiophene, and thiazole) and bridges (4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) and benzodithiophene (BDT)) as the central pi-spacers were synthes ...

American Chemical Society2012

High Efficiency Quantum Dot Heterojunction Solar Cell Using Anatase (001) TiO2 Nanosheets

Michael Graetzel, Mohammad Khaja Nazeeruddin, Lioz Etgar, Wei Zhang

Wiley2012

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

Michael Graetzel, Mohammad Khaja Nazeeruddin, Yonghui Lee

Iodide redox (3I(-)/I-3(-)), polysulfide redox (S2-/S-x(2-)), organic redox [TMTU/TMFDS2+: tetramethylthiourea/tetramethylformaminium-bis(trifluoromethanesulfonyl) imide], ferrocene redox (Fc/Fc(+)), nickel redox [Ni(II)/Ni(III)], and cobalt redox [Co(II)/ ...

Royal Society of Chemistry2012

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